Catalog · 249 calculators
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calculators
Every calculator in the Calcatalog — financial, health, math, and everyday tools. All results computed in your browser, free.
Mortgages, loans, retirement, investments
- 01 401k Early Withdrawal Penalty Calculate the true cost of an early 401(k) withdrawal — see the 10% penalty, estimated federal taxes, and the net amount you actually receive. Financial
- 02 Alimony Estimate monthly spousal support using the income gap model — enter both spouses' gross incomes and marriage length to get a ballpark alimony estimate. Educational purposes only; consult a family law attorney. Financial
- 03 Annuity Calculate the present value, future value, or payment for an ordinary annuity or annuity-due. Supports monthly, quarterly, semi-annual, and annual frequencies. Financial
- 04 APY to APR Convert between APY and APR for any compounding frequency. See the effective annual rate and the compounding premium for savings accounts, CDs, and loan comparisons. Financial
- 05 Auto Loan Calculate your monthly car payment, total cost, and full repayment schedule for any auto loan. Free and accurate. Financial
- 06 Bond Yield Calculate current yield, yield to maturity (YTM), and yield to call (YTC) for any bond. Uses semiannual compounding per US bond market convention. Financial
- 07 Break-Even Calculate your break-even point in units and revenue from fixed costs, price per unit, and variable cost per unit. Financial
- 08 Budget Calculator (50/30/20) Allocate your monthly or annual income using the 50/30/20 budgeting rule — 50% needs, 30% wants, 20% savings and debt — or set a custom split. Financial
- 09 Business Valuation Estimate your business value using the SDE or EBITDA multiple method — enter annual earnings and a valuation multiple to see enterprise value, equity value, and a ±0.5× sensitivity range. Educational estimate; consult a CVA for a formal appraisal. Financial
- 10 Capital Gains Tax Estimate your federal capital gains tax on the sale of a stock or asset — short-term vs. long-term rates, plus the 3.8% Net Investment Income Tax (NIIT) for 2026. Financial
- 11 Car Depreciation Calculate how quickly your car loses value year by year using declining-balance or straight-line depreciation, and see the total loss over your ownership period. Financial
- 12 Car Lease Calculate your estimated monthly car lease payment from MSRP, selling price, residual value, money factor, and lease term. Financial
- 13 CD APY Calculate the maturity value and interest earned on a certificate of deposit, or convert a nominal APR to APY based on compounding frequency. Financial
- 14 Charitable Deduction Estimate your federal tax savings from charitable donations — enter your AGI, filing status, cash and property donations, and other itemized deductions to see your tax savings, effective donation cost, and whether itemizing makes sense. 2026 tax rules. Financial
- 15 Child Support Estimate monthly child support using the Income Shares Model — enter both parents' gross incomes, number of children, and add-on costs for a US-national approximation. Results are educational, not legal advice. Financial
- 16 College Savings Calculate the monthly contribution needed to reach a college cost target by enrollment, given your current savings and expected investment return. Financial
- 17 Compound Interest Calculate how your savings or investment grows with compound interest. See the impact of compounding frequency and regular contributions. Financial
- 18 Cost Per Use Calculate the true cost per use of any item and optionally compare two items to find the better value. Financial
- 19 Credit Card Minimum Payment See how long it takes to pay off a credit card balance with minimum-only payments and how much interest you will pay in total. Financial
- 20 Debt / Credit Card Payoff Find out exactly how long it will take to pay off your debt and how much interest you'll pay. Compare minimum payments vs. fixed payments. Financial
- 21 Debt-to-Income Ratio Calculate your front-end and back-end debt-to-income (DTI) ratio to see if you qualify for a mortgage or other loan. Includes lender tier guidance. Financial
- 22 Dividend Yield Calculate dividend yield, yield on cost, annual income, and monthly income from a dividend-paying stock or ETF. Financial
- 23 Emergency Fund Calculate how large your emergency fund should be and how long it will take to reach your target based on monthly expenses, coverage goal, and monthly savings. Financial
- 24 Employee Stock Option Estimate your net proceeds from exercising ISO or NSO stock options — enter strike price, current FMV, sale price, and tax rates to see exercise cost, AMT (ISO), ordinary income tax (NSO), capital gains tax, and net profit. Consult a CPA before exercising. Financial
- 25 Escrow Calculate your monthly escrow payment for property tax and homeowner's insurance. Add your P&I payment to see your full PITI mortgage payment in seconds. Financial
- 26 Estate Tax Estimate federal US estate tax using the 2026 exemption ($7,000,000) and 40% tax rate — enter gross estate, deductions, and liabilities to see your taxable estate and estimated tax. For planning only; consult an estate attorney. Financial
- 27 FIRE Calculate your FIRE number, years to financial independence, and FI age based on your savings, expenses, contributions, and expected real return. Financial
- 28 Home Affordability Find out how much house you can afford using the 28/36 DTI rule — enter your income, debts, down payment, rate, and term. Financial
- 29 Home Equity Calculate your current home equity, loan-to-value (LTV) ratio, and how much equity you can access through a HELOC or cash-out refinance at an 80% LTV threshold. Financial
- 30 HSA Contribution Calculate your 2026 HSA contribution limit and project your future balance — enter your coverage type, age, and months enrolled in an HDHP. Financial
- 31 Income Tax Withholding Estimate your federal income tax withheld per paycheck using 2026 IRS Publication 15-T tables — enter gross pay, pay frequency, filing status, and W-4 steps 2–4 to see per-period and annual withholding. For federal tax only. Financial
- 32 Inflation Calculate the equivalent buying power of a dollar amount between any two years from 1913 to 2024 using historical US BLS CPI-U data. Financial
- 33 Investment / ROI Calculate your return on investment (ROI), net gain, and annualized return for any investment. Free and instant. Financial
- 34 Lease vs. Finance Compare the true cost of leasing vs. buying a car over the same period. Correctly nets the financed vehicle's resale value — the most common mistake in online calculators. Financial
- 35 Life Insurance Needs Calculate how much life insurance you need using the DIME method — Debt, Income replacement, Mortgage, and Education costs — plus final expenses and existing coverage. Financial
- 36 Loan Payoff Extra Payment Calculate how extra monthly payments reduce payoff time and total interest on any installment loan — auto, personal, or student. Financial
- 37 Mortgage Calculate your monthly mortgage payment, total interest, and see a full amortization schedule. Free, accurate, and runs in your browser. Financial
- 38 Mortgage Payoff See how extra monthly principal payments reduce your mortgage payoff time and total interest paid. Financial
- 39 Mortgage Points Calculate whether buying discount points makes financial sense — compare the upfront cost of points against monthly savings to find your break-even timeline. Financial
- 40 Net Pay Raise Find out how much a salary raise actually adds to your take-home pay after federal income tax and FICA. See the annual, monthly, and biweekly net increase. Financial
- 41 Net Worth Calculate your net worth by subtracting your total liabilities from your total assets. See your financial snapshot in seconds. Financial
- 42 NPV Calculator (Net Present Value & IRR) Calculate net present value (NPV), internal rate of return (IRR), and payback period for any investment with multiple future cash flows. Financial
- 43 Overdraft Fee See how much overdraft fees cost you per year — enter your per-event fee, overdraft frequency, and extended fee details to see total annual cost, APR-equivalent rate, and savings from switching to overdraft protection. Financial
- 44 Overtime Pay Calculate your total pay including overtime earnings at 1.5× or 2× multipliers. Enter your base rate, regular hours, and overtime hours to see a full pay breakdown. Financial
- 45 Payback Period Calculate how many years it takes to recover a capital investment. Find both simple payback period and discounted payback period (NPV-based) with a year-by-year table. Financial
- 46 Payroll Tax Calculate employee and employer FICA payroll taxes — Social Security (6.2%), Medicare (1.45%), Additional Medicare Tax (0.9%) — for W-2 employees and self-employed individuals. Uses 2026 rates. Financial
- 47 Personal Loan Calculate monthly payments, total interest, and amortization for any personal or installment loan. Free and instant. Financial
- 48 Portfolio Rebalancing Calculate exactly how much to buy or sell in each asset class to rebalance your portfolio to target allocations. Supports up to 25 asset classes. Financial
- 49 Profit and Loss Calculate gross profit, net profit, and profit margin percentages from revenue, cost of goods sold, and operating expenses. Financial
- 50 Refinance See if refinancing makes sense — compare your current mortgage to a new loan, calculate your break-even point, and total savings. Financial
- 51 Rent vs. Buy Should you rent or buy a home? This calculator uses a year-by-year simulation with PMI auto-removal, home appreciation, and opportunity cost of the down payment to find the true break-even year. Financial
- 52 Rental Property Cash Flow Calculate monthly and annual rental property cash flow, NOI, and cash-on-cash return. Enter rent, vacancy, purchase price, financing, and operating expenses for a complete landlord analysis. Financial
- 53 Rental Yield Calculate gross yield, net yield, cap rate, cash-on-cash return, and the 1% rule for any rental property. Computes your mortgage payment automatically from loan amount, rate, and term. Financial
- 54 Required Minimum Distribution (RMD) Calculate your annual RMD from a traditional IRA or 401(k) using the IRS Uniform Lifetime Table. Enter your account balance and age to find out how much you must withdraw. Financial
- 55 Retirement / 401(k) Project your 401(k) or retirement account balance at retirement based on current savings, contributions, employer match, and expected growth. Financial
- 56 Reverse Mortgage Estimate your HECM reverse mortgage proceeds — principal limit, net available lump sum, and estimated monthly tenure payment — based on your home value, age, and current interest rate. Financial
- 57 Roth IRA Contribution Limit Find your 2026 Roth IRA contribution limit after the MAGI phase-out — enter your income, filing status, and age. Financial
- 58 Salary to Hourly Convert an annual salary to an hourly rate. Adjust hours per week and weeks per year for part-time, contract, or full-time schedules. Includes weekly, biweekly, and monthly pay breakdowns. Financial
- 59 Sales Tax Calculate sales tax and total purchase price instantly. Enter any price and tax rate — or reverse-calculate the pre-tax price. Financial
- 60 Savings Bond Estimate the projected value of US Series I Bonds and EE Bonds — enter purchase amount, hold period, and bond type to see projected growth, interest earned, and effective APY. Rates updated May 2025. Financial
- 61 Savings Goal Calculate the monthly, quarterly, or annual contribution needed to reach a savings target by a specific date, given an interest rate. Financial
- 62 Savings Rate Calculate your savings rate as a percentage of gross or net income, and see how many years you need to reach financial independence. Financial
- 63 Scholarship Savings Calculate how much to save monthly in a 529 plan to cover college costs after expected scholarships and grants — enter total cost, aid, current savings, years, and growth rate to see your monthly savings target. Financial
- 64 Self-Employment Tax Calculate your self-employment (SE) tax and above-the-line deduction for freelancers, sole proprietors, and independent contractors. Uses 2026 IRS FICA rates. Financial
- 65 Simple Interest Calculate simple interest earned or charged on a loan or deposit using the formula I = P × r × t. Financial
- 66 Social Security Find your monthly Social Security benefit at any claiming age from 62 to 70, and discover when claiming later pays off with a nominal breakeven analysis. Financial
- 67 Stock Average Calculator (Cost Basis) Calculate the average cost per share across multiple stock purchases (lots), grouped by ticker. Enter each lot's ticker, price, and share count to find your weighted average cost basis, plus per-ticker and portfolio unrealized gain or loss. Financial
- 68 Take-Home Paycheck Calculate your net take-home pay after federal income tax, Social Security, and Medicare. Enter your gross pay, filing status, and deductions. Financial
- 69 Tax Bracket Find your federal income tax bracket, marginal rate, effective rate, and total tax owed for 2026 — with a full per-bracket breakdown. Financial
BMI, nutrition, fitness, body metrics
- 01 A1C / eAG Convert between A1C percentage and estimated average glucose (eAG) in mg/dL or mmol/L using the ADA-validated formula. Health
- 02 Alcohol Calorie Calculate calories in alcoholic drinks from ABV%, serving volume, and drink count. See your session total, alcohol grams, and standard US drinks. Health
- 03 Anemia Risk Score Estimate your risk of anemia by checking common symptoms and known risk factors. Get a risk score and tier to help decide whether to discuss a blood test with your doctor. Health
- 04 BAC Estimate blood alcohol content using the Widmark formula. For harm-reduction awareness only — never use to decide whether to drive. Health
- 05 Biological Age Estimate your biological age from your date of birth and lifestyle factors including exercise, sleep, diet, smoking, and stress. See how your habits affect your estimated functional age. Health
- 06 Blood Pressure Check your blood pressure reading against the ACC/AHA 2017 guidelines. Enter your systolic and diastolic numbers to find your category — Normal, Elevated, Stage 1, Stage 2, or Crisis. Health
- 07 Blood Sugar Converter Convert blood glucose between mg/dL and mmol/L, and convert A1C to estimated average glucose (eAG) or vice versa. For informational use only. Health
- 08 BMI Calculate your Body Mass Index (BMI) from height and weight, in metric or imperial units. See your WHO weight category and healthy weight range. Health
- 09 BMI Prime Calculate your BMI Prime — the ratio of your BMI to 25 — for a quick "how far from normal" measure alongside a plain-language interpretation and your ideal weight at a target BMI Prime. Health
- 10 BMR Calculate your Basal Metabolic Rate (BMR) — the calories your body burns at rest — using the Mifflin-St Jeor equation, with Harris-Benedict as an alternate. Health
- 11 Body Adiposity Index (BAI) Estimate body fat percentage using the BAI formula (Bergman 2011) from hip circumference and height alone — no weight required. Supports metric and imperial units. Health
- 12 Body Fat Estimate your body fat percentage with the US Navy circumference method from neck, waist, hip, and height measurements, in metric or imperial units. Health
- 13 Body Frame Size Determine your body frame size — small, medium, or large — using either the elbow-breadth method (a measured bone width) or the wrist-to-height ratio method. Useful context for interpreting ideal body weight ranges. Health
- 14 Body Surface Area Estimate your body surface area in square metres using the Mosteller and Du Bois formulas. For informational use — not for clinical drug dosing. Health
- 15 Calorie Cycling Calculate high-day and low-day calorie targets for a calorie-cycling (zigzag dieting) protocol from your weekly calorie goal and split pattern. Health
- 16 Calorie Deficit Calculate your daily calorie deficit or surplus from your TDEE and target intake, and estimate how long it will take to reach your weight goal. Health
- 17 Calories Burned Estimate calories burned during exercise using the MET method. Select from 20+ activities, enter your weight and duration. Health
- 18 Calories From Macros Calculate total calories from grams of protein, carbohydrates, and fat. See your macro ratio split and compare to a calorie goal. Health
- 19 Cardio Training Load Score your cardio session by heart rate effort, not just speed or calories. Uses the TRIMP method to award points based on how hard you actually worked relative to your heart rate reserve. Health
- 20 Cholesterol Ratio Calculate your Total/HDL and LDL/HDL cholesterol ratios with AHA risk-band interpretation — enter your cholesterol panel numbers to understand your cardiovascular risk profile. Health
- 21 Conception Estimate your likely conception date and fertile window from a due date or last menstrual period (LMP). Informational only — not for contraception. Health
- 22 Cortisol Stress Score Calculator (PSS-10) Measure your perceived stress level with the validated Cohen Perceived Stress Scale (PSS-10) — a 10-question questionnaire used in stress research worldwide. Health
- 23 Creatine Dose Calculate your creatine loading phase dose and daily maintenance dose based on body weight — using the ISSN evidence-based per-kilogram protocol. Health
- 24 Due Date Calculator (LMP Method) Estimate your pregnancy due date from your last menstrual period (LMP) using Naegele's Rule. Includes gestational age in weeks and days, trimester boundaries, and cycle-length adjustment. Health
- 25 Due Date from Ultrasound Calculate your estimated due date from a first-trimester ultrasound crown-rump length (CRL) or gestational age measurement. Uses the Hadlock 1992 CRL formula per ACOG guidance. Health
- 26 Fertility Window Estimate your fertile window — the days each cycle when conception is most likely — based on your last menstrual period and average cycle length. See your ovulation date and the next two upcoming fertile windows. Health
- 27 Free Testosterone Calculator (Vermeulen Equation) Calculate free and bioavailable testosterone from total T, SHBG, and albumin using the validated Vermeulen equation (J Clin Endocrinol Metab 1999). Health
- 28 Healthy Weight Range Find the healthy weight range for your height using the WHO BMI normal band (18.5–24.9), with your position in the range and how much weight gain or loss would bring you within it. Health
- 29 Heart Rate Zones Calculate your 5 training heart rate zones from age-predicted max HR (Fox or Tanaka formula). Shows bpm boundaries and training purpose for each zone. Health
- 30 Hydration Calculate your recommended daily water intake based on body weight, activity level, and climate. Adjusts for exercise and hot or humid environments using NAM / IOM and ACSM guidelines. Health
- 31 Ideal Weight Estimate your ideal body weight from height and biological sex using the Devine, Robinson, and Hamwi clinical formulas, in metric or imperial units. Health
- 32 Insulin Sensitivity Factor Calculator (1800 / 1700 Rule) Calculate your insulin sensitivity factor (ISF) — how much 1 unit of insulin lowers your blood glucose — using the 1800 Rule (rapid-acting) or 1700 Rule (regular insulin). Optionally estimate a correction dose for a given blood glucose reading. Health
- 33 IVF Due Date Calculate your estimated due date from your IVF embryo transfer date. Supports day-5 blastocyst, day-3 cleavage, and day-0 fresh transfers with ACOG / ASRM formula. Health
- 34 Keto Macro Calculate your daily keto macro targets — net carbs, protein, and fat in grams — from your calorie goal and macro percentages. Health
- 35 Lean Body Mass Calculate your lean body mass — total weight minus body fat — using the Boer and James clinical formulas, in metric or imperial units. Health
- 36 Macronutrient Convert a daily calorie target into protein, carbohydrate, and fat gram targets using a customisable macro split. Health
- 37 Max Heart Rate Calculate your age-predicted maximum heart rate using three formulas — Fox (220−age), Tanaka (208−0.7×age), and Gellish (207−0.7×age) — and compare the results side-by-side. Health
- 38 Menopause Symptom Score Calculator (Greene Climacteric Scale) Score your menopause symptoms using the validated 21-item Greene Climacteric Scale (GCS), with subscale breakdowns for anxiety, depression, somatic, vasomotor, and sexual symptoms. Health
- 39 Miscarriage Risk Estimate early pregnancy loss risk by maternal age, prior pregnancy losses, and whether a fetal heartbeat has been confirmed on ultrasound. Health
- 40 Net Carbs Calculate net carbs by subtracting dietary fiber and sugar alcohols from total carbohydrates. Track net carb intake for keto and low-carb diets. Health
- 41 One-Rep Max Estimate your one-rep max (1RM) from any weight and rep count using six sports-science formulas — Brzycki, Epley, Lombardi, Mayhew, O'Conner, and Wathan — in lb or kg. Health
- 42 Ovulation Estimate your ovulation date and fertile window from your last menstrual period and cycle length. Health
- 43 Pace Calculate your running or walking pace in minutes per mile or per kilometre, and your speed in mph or km/h. Enter any distance and time. Health
- 44 Pediatric BMI Calculator (CDC BMI-for-Age Percentile) Calculate your child's BMI percentile using CDC 2000 Growth Charts for ages 2–19. See the BMI-for-age percentile and weight-status category (Healthy weight, Overweight, Obese, Underweight). Health
- 45 Period Predictor Predict your next period and fertile window from your last menstrual period date and average cycle length. Estimates ovulation date and days until your next cycle. Health
- 46 Postpartum Weight Loss Estimate your postpartum weight-loss timeline and daily calorie guidance based on ACOG 2015 guidelines. Adjusts for breastfeeding status and IOM recommended rate of 1 lb/week. Health
- 47 Pregnancy Due Date Estimate your baby's due date using Naegele's Rule (LMP + 280 days) or your conception date. Adjusts for non-28-day cycles. Health
- 48 Pregnancy Weight Gain Calculate your recommended pregnancy weight gain range by pre-pregnancy BMI using IOM 2009 guidelines. Track how much weight gain is expected each week. Health
- 49 Protein Intake Find your daily protein target in grams based on body weight and activity level, using ISSN and USDA reference ranges. Health
- 50 Race Time Predictor Predict your finish time at any race distance from a recent result using the Riegel formula. Supports 800 m through 100 miles plus custom distances. Health
- 51 Resting Metabolic Rate Calculator (Mifflin-St Jeor) Calculate your resting metabolic rate (RMR) using the Mifflin-St Jeor equation — the most clinically validated method for adults. Optionally add lean body mass for the Cunningham formula, which is more accurate for athletes. Health
- 52 Sleep Cycle Find the best time to go to sleep or wake up based on 90-minute sleep cycles. Uses sleep-onset latency to recommend times that complete full REM cycles. Health
- 53 Sleep Debt Track your cumulative sleep debt by logging actual vs. target hours over multiple nights. See total hours owed and how long recovery will take. Health
- 54 Sleep Needs by Age Look up the National Sleep Foundation recommended sleep hours for your age group and see if you're getting enough sleep with a surplus or deficit readout. Health
- 55 Steps to Miles Convert steps to miles or kilometers and estimate calories burned. Stride length is calculated from your height and sex using the ACSM formula. Health
- 56 Swimming Pace Calculate your swim pace per 100 m or per 100 yd from distance and finish time. Generates a lap-by-lap splits table for metric and yards pools. Health
- 57 Target Heart Rate Find your aerobic training zones using the Karvonen heart rate reserve method. Shows five intensity zones from light to maximal, with Fox and Tanaka max-HR options. Health
- 58 TDEE Calculate your Total Daily Energy Expenditure (TDEE) — the calories you burn per day — from BMR and activity level, plus weight-loss and weight-gain targets. Health
- 59 VO2max Estimate your VO₂max (maximal oxygen uptake) using the Cooper 12-minute run, Rockport 1-mile walk test, or the heart rate ratio method. Get your cardiovascular fitness category. Health
- 60 Waist-to-Height Ratio Calculate your waist-to-height ratio (WHtR) and see your health-risk category. The simple "keep your waist less than half your height" rule. Supports metric and imperial. Health
- 61 Waist-to-Hip Ratio Calculate your waist-to-hip ratio and see your WHO metabolic risk category. Supports metric and imperial measurements. Health
- 62 Water Intake Get your daily water target from the body-weight method and the IOM Adequate Intake, in oz or millilitres. Health
Percentages, statistics, algebra, geometry
- 01 Area Calculate the area of a circle, rectangle, triangle, trapezoid, ellipse, or parallelogram. Shows the formula used for each shape. Math
- 02 Average Find the arithmetic mean of any list of numbers. Also shows sum, count, minimum, and maximum. Math
- 03 Binomial Probability Calculate P(X=k), P(X≤k), or P(X≥k) for a binomial distribution B(n,p) using the exact PMF. Includes a PMF bar chart for up to 50 trials. Math
- 04 Circle Find any circle measurement — radius, diameter, circumference, or area — from any single known value. Enter one quantity and get all four instantly. Math
- 05 Confidence Interval Calculate the confidence interval for a population mean from your sample mean, standard deviation, and sample size at 90%, 95%, or 99% confidence. Math
- 06 Coordinate Distance Calculate the distance between two points in 2D or 3D, plus the midpoint and slope. Supports negative coordinates. Math
- 07 Distance Calculate the Euclidean distance between two points in 2D or 3D space. Math
- 08 Exponent Raise any base to any power — positive, negative, or fractional — with domain error detection for undefined results. Math
- 09 Fibonacci Find the Nth Fibonacci number or list the first N terms of the Fibonacci sequence. Supports up to F(100) with exact integer precision. Math
- 10 Fraction Simplify a fraction to its lowest terms, or add two fractions and get the result in simplified form. Uses GCD reduction. Math
- 11 GCF and LCM Find the Greatest Common Factor (GCF) and Least Common Multiple (LCM) of any list of integers using Euclid's algorithm. Math
- 12 Geometric Sequence Find the Nth term and sum of a geometric or arithmetic sequence. Enter the first term, common ratio (or difference), and N to get results instantly. Math
- 13 Law of Cosines Solve any triangle using the law of cosines. Enter three sides (SSS) or two sides and the included angle (SAS) to find all angles, area, and perimeter. Math
- 14 Law of Sines Solve triangles using the law of sines. Supports ASA, AAS, and SSA modes. The SSA ambiguous case shows 0, 1, or 2 valid solutions automatically. Math
- 15 Linear Equation Solve systems of 2 or 3 linear equations with step-by-step solutions. Detects unique solutions, no solution (parallel lines), and infinitely many solutions. Math
- 16 Logarithm Calculate the natural log, log base 10, log base 2, or any custom base logarithm. Results to 6 significant figures with full domain validation. Math
- 17 Lottery Odds Calculate exact lottery prize-tier odds for any pool size. See "1 in X" probability and percentage for the jackpot and every lower prize tier — configurable for Powerball, Mega Millions, or any lottery. Math
- 18 Margin and Markup Calculate gross margin % and markup % from cost and price — both displayed together so you can see exactly how the two differ and avoid the most common pricing mistake. Math
- 19 Matrix Calculate the determinant or inverse of a 2×2 or 3×3 matrix, or add and multiply two matrices. Guards against singular matrices (det = 0) with a clear error rather than NaN. Math
- 20 Mean, Median and Mode Find the mean (average), median (middle value), and mode (most frequent value) of any list of numbers. Math
- 21 Modulo Calculate the remainder of a division (modulo) for any integers, including negatives. Choose between truncated (JavaScript/C) and floored (Python) convention. Math
- 22 Number Sequence Detect whether a number sequence is arithmetic, geometric, or Fibonacci-like, then extend it by up to 20 more terms. Math
- 23 Password Strength Estimator — Check How Strong Your Password Is Estimate the strength of a password using Shannon entropy and pattern analysis. See entropy bits, character class coverage, pattern deductions, and a strength tier — all calculated locally, never sent to a server. Math
- 24 Percentage Calculate X% of Y, percentage change between two values, or percentage difference. Three modes in one calculator. Math
- 25 Percentage Change Calculate the percentage increase or decrease between two values. Handles positive, negative, and zero-result cases with clear directional output. Math
- 26 Permutation and Combination Calculate nPr (ordered permutations) and nCr (unordered combinations). Handles very large n using BigInt — no silent Infinity. Math
- 27 Polynomial Root Find the roots of linear, quadratic, cubic, and quartic polynomials. Handles real and complex roots with numerically stable methods. Math
- 28 Prime Factorization Find the prime factorization of any number up to 10¹⁵. See the prime factors and exponent notation instantly. Math
- 29 Probability Calculate simple event probability, the complement (probability of not A), or the joint probability of two independent events. Math
- 30 Proportion Solve a proportion a/b = c/d for any unknown term. Enter the three known values and select which one is missing. Math
- 31 Quadratic Equation Solve ax² + bx + c = 0 with a numerically-stable algorithm. Handles two real roots, one repeated root, and complex roots (no real solutions). Math
- 32 Random Number Generate a random integer within any range you specify. Runs entirely in your browser — no server, no logging. Math
- 33 Ratio Simplify a ratio to its lowest terms, or solve a proportion a:b = c:? to find the missing fourth term. Math
- 34 Roman Numeral Converter Convert any integer from 1 to 3999 to Roman numerals, or convert a Roman numeral back to an integer. Validates both directions and rejects non-standard forms like IIII or VV. Math
- 35 Rounding Round any number to a specified number of decimal places using half-up (standard) or half-even (banker's) rounding. Supports negative decimal places. Math
- 36 Scientific A full-featured scientific calculator with basic arithmetic, square root, squaring, reciprocal, percent, and ±. Keyboard-accessible with roving focus navigation. Math
- 37 Scientific Notation Convert numbers to and from scientific notation (m × 10^e). Supports 6 significant figures for the mantissa. Math
- 38 Set Theory Compute set union, intersection, difference, symmetric difference, complement, subset checks, and power sets. Enter elements as comma-separated lists. Math
- 39 Significant Figures Count significant figures in any number or round to N sig figs instantly. Handles leading zeros, trailing zeros, and scientific notation correctly. Math
- 40 Slope Find the slope, y-intercept, equation, and angle of a line through two points. Handles vertical lines (undefined slope). Math
- 41 Standard Deviation Calculate population and sample standard deviation and variance from a list of numbers. Uses the numerically stable two-pass algorithm. Math
- 42 Triangle Solve a triangle from three sides (SSS), two sides and an angle (SAS), or a right triangle from two sides. Computes all angles, area, and perimeter. Math
- 43 Truth Table Generate truth tables for any logical expression with up to 4 variables (A, B, C, D). Supports AND, OR, NOT, XOR, IMPLIES, IFF, and Unicode logic symbols. Math
- 44 Unit Rate Calculate unit rates and their inverses. Enter a quantity, the "per" amount, and your unit labels to get the rate per unit and the inverse rate. Math
- 45 Vector Calculate dot products, cross products, magnitudes, angles, and vector addition or subtraction for 2D and 3D vectors. Math
- 46 Weighted Average Calculate the weighted average of any set of values. Add rows, enter each value and its weight, and get the exact Σ(v×w)/Σ(w) result with a per-row breakdown. Math
- 47 Z-Score Calculate z-scores, p-values, and percentiles from any observation using the standard normal distribution. Also find the z-score for any percentile (inverse). Math
Unit converters, date & time, everyday tools
- 01 Add/Subtract Days Add or subtract any number of days from a date. Enter a negative number of days to subtract. Handles month and year boundaries automatically. Other
- 02 Age Calculate your exact age in years, months, and days from your date of birth. Handles Feb-29 birthdays and shows your next birthday. Other
- 03 Age in Days Calculate your exact age in total days, weeks, months, and years from your date of birth. Enter a custom reference date to calculate between any two dates. Other
- 04 Angle Converter Convert between degrees, radians, gradians (gon), arcminutes, arcseconds, and turns using exact ISO 31-1 mathematical relationships. Other
- 05 Area Converter Convert between square millimetres, centimetres, metres, kilometres, inches, feet, yards, acres, hectares, and square miles. Exact NIST-derived factors. Other
- 06 Aspect Ratio Calculate the aspect ratio of any image, video, or screen, and scale dimensions proportionally. Simplifies ratios like 1920×1080 to 16:9 and computes missing width or height. Other
- 07 Base Converter Convert numbers between binary, octal, decimal, and hexadecimal — instantly. Handles 64-bit integers correctly using BigInt (no precision loss above 2^53). Other
- 08 Bitwise Perform AND, OR, XOR, NOT, left-shift, and right-shift on any integers at 8/16/32/64-bit widths — with correct two's-complement signed interpretation. Other
- 09 BTU Estimate the air conditioner or heater size needed for any room. Based on ACCA rule-of-thumb sizing — adjust for sunlight and occupancy. Results are ballpark estimates only. Other
- 10 Business Days Count the working days between two dates, excluding weekends and US federal holidays. Uses the OPM 2026 federal holiday calendar with observed-weekday shifting. Other
- 11 Carbon Footprint Calculator — Estimate Your Annual CO₂ Emissions Estimate your annual personal carbon footprint in metric tons CO₂e. Enter your driving, home energy use, diet, and flights to see your total and how it compares to the US average. Other
- 12 Clothing Size Converter Convert clothing sizes between US, UK, EU, and International (XS/S/M/L/XL) for women's and men's tops and bottoms. Other
- 13 Concrete Calculate cubic yards and how many bags of concrete to buy for any slab or footing. Bags are always rounded up; bag yield is flagged as manufacturer-specific. Other
- 14 Concrete Steps Calculate concrete volume and bags needed for steps from riser height, tread depth, step count, and width. Includes IRC 2021 riser and tread code compliance check. Other
- 15 Cooking Unit Converter Convert between cups, tablespoons, teaspoons, fluid ounces, pints, quarts, gallons, and millilitres. Also converts grams, ounces, and pounds for baking. Other
- 16 Countdown Count down the days, hours, minutes, and seconds to any future date — or see how much time has passed since a past date. Updates live every second. Other
- 17 Currency Converter Convert any amount between two currencies using your own exchange rate. Enter today's rate from your bank — no live data, no fees, no surprises. Other
- 18 Data Size Converter Convert between bytes, kilobytes, megabytes, gigabytes and more. Switch between SI (1000-based, kB/MB/GB) and IEC (1024-based, KiB/MiB/GiB) with explicit labeling. Other
- 19 Date Difference Calculate the number of calendar days, months, and years between two dates. Uses UTC calendar arithmetic — accurate across daylight saving time transitions. Other
- 20 Day of the Week Find out what day of the week any date falls on — past, present, or future. Works correctly for leap years, century years, and dates as far back as the Gregorian calendar. Other
- 21 Deck Calculate lumber board count, joist and beam estimates, and material cost for your deck project. Enter your deck dimensions and get an instant material estimate. Other
- 22 Discount Calculate the sale price after one or more stacked discounts. Works correctly for stacked percentage-off deals — avoiding the common 30%-vs-28% error. Other
- 23 Drywall Calculate sheets of drywall needed from room dimensions and door/window cutouts. Choose 4×8 or 4×12 sheet size. Includes joint compound estimate. Other
- 24 Electricity Cost Calculate how much a device costs to run per day, month, and year. Enter wattage, daily hours, and your electricity rate — defaults to the US average of $0.16/kWh. Other
- 25 Energy Converter Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and foot-pounds using exact NIST-defined conversion factors. Other
- 26 Fence Post Calculate how many fence posts, rails, and panels you need for a single run or enclosed yard. Includes post hole depth, concrete bags to buy, and optional cost estimate. Other
- 27 Fencing Calculate linear feet of fencing, post count, and panel count for any yard. Supports rectangle mode and custom side lengths. Add cost per linear foot for a total estimate. Other
- 28 Flooring Calculate square footage of flooring needed with waste factor, number of boxes from coverage per box, and total cost estimate for any room. Other
- 29 Fuel Cost Calculate trip fuel cost in seconds. Works in US units (miles/mpg/$/gal) and metric (km/L per 100km/$/L). See total cost, fuel used, and cost per mile or km. Other
- 30 Fuel Economy Converter Convert fuel economy between MPG (US), MPG (UK/Imperial), L/100km, and km/L. Handles the inverted L/100km relationship correctly using exact NIST factors. Other
- 31 GPA Calculate your GPA on a 4.0 unweighted, weighted 5.0 (AP/honors), or 100-point scale. Add any number of courses and credit hours for an accurate weighted average. Other
- 32 Grade Find out what score you need on your final exam to reach your target grade. Handles any exam weight percentage — instantly shows if your goal is achievable. Other
- 33 Grade Needed Calculator — What Grade Do I Need on My Final? Find out exactly what score you need on your final exam to achieve your target course grade. Enter your current grade, the weight of work done so far, and your desired overall grade. Other
- 34 Gravel Calculate cubic yards and tons of gravel or crushed stone needed from area and depth. Choose rock type for accurate weight, plus bags-vs-bulk toggle and cost estimate. Other
- 35 Insulation Calculate insulation R-value, thickness, and material quantity (bags or batts) by US climate zone per IECC 2021 Table R402.1.2. Covers attic, wall, floor, and crawlspace. Other
- 36 Length Converter Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles. Uses exact NIST-defined conversion factors. Other
- 37 Lumber Calculate board feet and pieces of lumber needed for any project. Enter board dimensions and piece count — includes a 15% waste allowance and optional cost estimate. Other
- 38 Mulch Calculate cubic yards of bulk mulch (or number of 2 cu ft bags) needed to cover any garden bed or landscaped area. Always rounded up. Other
- 39 Number Words Convert any integer to its written English form. Enter a number and instantly see it spelled out in words — useful for checks, legal documents, and programming. Other
- 40 Paint Calculate how many gallons of paint to buy for any room. Enter wall area, number of coats, and deduct doors and windows — results are rounded up so you never run short. Other
- 41 Pool Volume Calculate swimming pool water volume in gallons and cubic feet for rectangular, oval, and round pools. Includes fill time estimate based on your hose flow rate. Other
- 42 Reading Time Calculator — How Long Will It Take to Read? Find out exactly how long it takes to read any piece of text. Enter the word count and your reading speed to get an estimated reading time in minutes and seconds. Other
- 43 Recipe Scaling Scale any recipe up or down instantly. Enter original and desired servings, then add ingredients with quantities to see original and scaled amounts side-by-side. Other
- 44 Retirement Age Calculate how many years, months, and days remain until your target retirement age or a specific retirement date. Includes your Social Security Full Retirement Age for reference. Other
- 45 Ring Size Convert finger circumference or diameter to US, UK, EU, and Japan ring sizes. Or look up circumference and diameter from a US size. Other
- 46 Roman Numeral Date Convert any Gregorian date to Roman numerals (day · month · year) for wedding invitations, engravings, or monuments — or decode a Roman numeral date back to a calendar date. Other
- 47 Roofing Calculate squares of shingles, underlayment rolls, and ridge cap bundles needed for any roof from footprint area and pitch. Includes optional cost estimate. Other
- 48 Sand Calculate cubic yards and tons of sand needed from area and depth. Choose sand type for accurate weight estimates, plus bags-vs-bulk toggle and cost estimate. Other
- 49 Shoe Size Converter Convert shoe sizes between US, UK, EU, and Mondopoint (cm foot length) for women and men. Find your size in any system. Other
- 50 Speed Converter Convert between metres per second, kilometres per hour, miles per hour, feet per second, and knots. Uses exact NIST-defined conversion factors. Other
- 51 Split Bill Split any restaurant bill evenly — with tip — and never be $0.01 short. Uses carry-remainder allocation so every cent is accounted for. Other
- 52 Square Footage Calculate the exact square footage (or square metres) of a rectangular room or area by entering length and width. Instant, accurate, and unit-aware. Other
- 53 Square Yards Convert room dimensions from square feet to square yards for carpet and flooring orders. Includes waste factor and linear yards estimate for standard 12 ft carpet rolls. Other
- 54 Stair Calculate the number of risers, tread depth, total rise and run, and stringer length for any staircase from floor-to-floor height. Includes IRC 2021 code compliance check. Other
- 55 Temperature Converter Convert between Celsius, Fahrenheit, and Kelvin instantly. Enter one temperature and see all three scales simultaneously. Uses exact affine transforms — not ratios. Other
- 56 Tile Calculate how many tiles you need for any room — with automatic waste factor for straight or diagonal layouts. Results are rounded up so you're never short. Other
- 57 Time Between Dates Calculate how much time is between two dates — in days, weeks, hours, and a years/months/days breakdown. Perfect for payroll, project timelines, and scheduling. Other
- 58 Time Card Enter clock-in and clock-out times to calculate total hours worked, with optional unpaid break deduction. Returns results in both decimal hours and HH:MM format. Other
- 59 Time Duration Convert between HH:MM:SS and decimal hours for timesheets and payroll. Handles minute and second overflow automatically (75 minutes → 1h 15m). Other
- 60 Timezone Converter Convert times between timezones — Eastern, Pacific, GMT, Tokyo, Sydney, and 20+ more — with correct DST handling for any date. Other
- 61 Tip by Item Calculator — Split the Bill Fairly by What You Ordered Split a restaurant bill fairly when everyone ordered different amounts. Assign each item to a diner and set the tip — each person pays for their items plus a proportional share of the tip. Other
- 62 Tip Calculate the exact tip and total for any bill. Choose 10%, 15%, 18%, 20%, or enter a custom percentage — instant results with no guessing. Other
- 63 Topsoil Calculate cubic yards and bags of topsoil needed for a lawn, garden bed, or raised bed. Instant bulk order quantity, weight estimate, and optional cost estimate. Other
- 64 Unit Price Compare the true cost per unit of two products — even in different package sizes or units. Instantly see which size or brand is the better value. Other
- 65 Volume Converter Convert between US and imperial (UK) volume units. Includes gallons, pints, quarts, fluid ounces, cups, and litres. US and imperial units are clearly separated to prevent errors. Other
- 66 Wallpaper Calculate how many wallpaper rolls you need from room perimeter, wall height, doors, windows, and pattern repeat. Includes waste for pattern matching. Other
- 67 Week Number Find the ISO 8601 week number for any date. Handles year-boundary traps where December dates fall in week 1 of the next year, or January dates belong to the previous year's week 53. Other
- 68 Weight Converter Convert between milligrams, grams, kilograms, metric tonnes, ounces, pounds, stone, and US/UK tons. Uses exact NIST-defined conversion factors. Other
- 69 Window Replacement Estimate window replacement cost, total glass area, and material quantities for your home window replacement project. Enter window count, size, and type for an instant rough estimate. Other
- 70 Words to Pages Calculator — How Many Pages Is My Word Count? Convert word count to an approximate page count for academic and professional documents. Choose font size (10/11/12pt) and line spacing (single/double) to match your format. Other
- 71 Work Hours Calculate total weekly hours worked from daily clock-in and clock-out times. Supports up to 7 days, overnight shifts, and a configurable overtime threshold. Other
Showing all 249 calculators across 4 categories.