HEALTH · CALORIE DEFICIT

Calorie Deficit Calculator

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.

Your Calories

Your estimated maintenance calories

Your planned daily calorie intake

Negative = lose weight, positive = gain weight, 0 = no goal

→ Result
Daily Deficit
500 kcal/day deficit
Maintenance (TDEE)2,500 cal/day
Target intake2,000 cal/day
Time to goal (10 lbs)~10 weeks (70 days)

Time-to-goal uses the 3,500 kcal ≈ 1 lb approximation (NIH/Mayo Clinic). Actual results vary; this model does not account for metabolic adaptation.

About This Calculator

A calorie deficit is the cornerstone of evidence-based weight management. This calculator takes your Total Daily Energy Expenditure (TDEE — your maintenance calories) and your planned daily intake, then shows you the size of your deficit or surplus and estimates how long it will take to reach a weight goal using the widely-accepted 3,500-kcal-per-pound approximation from the NIH and Mayo Clinic.

How It Works

Enter your TDEE (use the TDEE Calculator if you don't know it), your planned daily calorie intake, and an optional weight goal in pounds. The calculator computes your daily deficit (TDEE minus intake) or surplus (intake minus TDEE). If you set a goal, it estimates days and weeks using the 3,500-kcal rule: each pound of fat stores approximately 3,500 kcal, so dividing your goal by your daily deficit gives the expected timeline.

The Formula

Deficit = TDEE − Daily Intake Days to goal = Goal (lbs) × 3,500 ÷ |Deficit|

TDEE
Total Daily Energy Expenditure — your maintenance calorie level
Daily Intake
Your planned calorie consumption per day
Goal (lbs)
Desired weight change in pounds (positive = gain, negative = loss)

Frequently Asked Questions

What is a calorie deficit?
A calorie deficit occurs when you consume fewer calories than your body burns in a day (your TDEE). Over time, your body draws on stored energy — primarily body fat — to make up the difference, resulting in weight loss. A deficit of roughly 500 kcal/day is typically associated with losing about 1 pound per week, though individual results vary.
Is the 3,500-kcal-per-pound rule accurate?
The 3,500-kcal rule is a useful approximation for short-term estimates, but research (Hall et al., Lancet 2011) shows it overpredicts long-term weight loss because metabolism adapts as you lose weight. It is most reliable for estimating outcomes over a few weeks. For long-term planning, expect your actual rate of loss to slow over time.
What is a safe calorie deficit?
Most guidelines recommend a deficit of 500–1,000 kcal/day, which corresponds to losing approximately 1–2 pounds per week. Deficits greater than 1,000 kcal/day (Very Low Calorie Diets) can cause muscle loss, nutritional deficiencies, and metabolic slowdown, and should only be done under medical supervision.
How do I find my TDEE?
Use the TDEE Calculator on this site. It combines your Basal Metabolic Rate (calculated with the Mifflin-St Jeor equation) with your activity multiplier to estimate the total number of calories your body burns each day, including exercise.