HEALTH · NET CARBS
Net Carbs Calculator
Calculate net carbs by subtracting dietary fiber and sugar alcohols from total carbohydrates. Track net carb intake for keto and low-carb diets.
"Net carbs" is a diet-community convention, not an FDA-defined term. Sugar alcohol impact on blood glucose varies by type — erythritol has minimal effect while maltitol may raise BG significantly. Individual responses vary; consult a healthcare provider for personalized dietary guidance.
About This Calculator
Net carbs are the digestible carbohydrates that actually affect blood sugar — total carbohydrates minus dietary fiber and sugar alcohols. This calculator lets you quickly compute net carbs from a nutrition label, with a transparent breakdown of every subtraction. It is designed for keto and low-carb diet tracking and is distinct from the Macronutrient Calculator, which works from calorie goals to derive gram targets.
How It Works
Read the three values from a food's nutrition facts label: total carbohydrates, dietary fiber, and sugar alcohols (if listed). Enter them below. The calculator subtracts fiber and sugar alcohols from total carbs to yield net carbs. The formula assumes these components have minimal blood-glucose impact for most people — note that individual responses vary, and some sugar alcohols (especially maltitol) can raise blood glucose more than others.
The Formula
Net carbs = total carbs − dietary fiber − sugar alcohols
- total carbs
- total carbohydrates in grams (nutrition facts label)
- dietary fiber
- grams of dietary fiber (nutrition facts label)
- sugar alcohols
- grams of sugar alcohols (optional nutrition facts line; use 0 if absent)
Frequently Asked Questions
- Do all sugar alcohols have zero impact on blood sugar?
- No — sugar alcohol glycaemic impact varies significantly by type. Erythritol has essentially no effect on blood glucose (~0 kcal/g). Xylitol and sorbitol have moderate effects. Maltitol has roughly 50–60% the glycaemic impact of glucose and can noticeably raise blood sugar in people with diabetes. The "subtract all sugar alcohols" rule is a simplification, not a guarantee.
- Why is net carbs not on the FDA nutrition label?
- The FDA does not recognize "net carbs" as an official nutrient declaration. Only "Total Carbohydrate" and its sub-components (dietary fiber, total sugars, added sugars) are regulated. The net-carb calculation is a convention popularized by low-carb and ketogenic diet communities.
- How many net carbs are allowed on a keto diet?
- Most ketogenic diet protocols target 20–50 g of net carbs per day to maintain nutritional ketosis, though the precise threshold varies by individual metabolism and activity level. This calculator is for tracking purposes only — consult a registered dietitian for personalized guidance.