Net Carbs Calculator
Net carbohydrates represent the carbs that your body actually digests and that impact blood sugar levels. For those following low-carb or ketogenic diets, tracking net carbs rather than total carbs allows inclusion of high-fibre vegetables and some sweeteners while staying within daily limits. The basic calculation subtracts dietary fibre from total carbohydrates shown on a nutrition label. For products containing sugar alcohols, the calculation becomes more nuanced: erythritol is typically fully subtracted, while other sugar alcohols are partially counted. This calculator handles all three scenarios and can also add up multiple food items to give you a meal or daily total, making it practical for everyday diet tracking.
Net carbs formula
Net Carbs = Total Carbs - Fibre - (Sugar Alcohols x Subtraction Factor)
Basic: Net Carbs = Total Carbs - Fibre
Subtraction factors: Erythritol = 1.0 (fully subtracted), mixed sugar alcohols = 0.5, maltitol = 0 (count fully).
Net carbs: frequently asked questions
What are net carbs?
Net carbs are the carbohydrates that your body digests and converts to glucose. They are calculated by subtracting dietary fibre from total carbohydrates. Some also subtract sugar alcohols, though their impact varies by type.
Why subtract fibre from carbohydrates?
Dietary fibre passes through the digestive system largely undigested and does not significantly raise blood glucose. Because it has no meaningful glycaemic impact, it is excluded from net carb counts used in low-carb and ketogenic diets.
Should I subtract sugar alcohols?
It depends on the type. Erythritol has minimal impact and is generally fully subtracted. Others like maltitol have a partial glycaemic effect and are typically counted at 50% impact. This calculator allows you to specify the portion of sugar alcohols to subtract.
How many net carbs per day for ketosis?
Most ketogenic diet protocols recommend staying below 20-50 g of net carbs per day to maintain nutritional ketosis. The exact threshold varies by individual. This calculator is informational; consult a registered dietitian for personalised guidance.
Are net carbs on US food labels?
US Nutrition Facts panels show total carbohydrates, dietary fibre, and total sugars separately but do not list 'net carbs.' You must calculate net carbs yourself by subtracting the fibre grams from total carbohydrates shown on the label.
Official sources
- U.S. Food and Drug Administration: Nutrition Facts Label - Daily Values.
- National Institutes of Health - Office of Dietary Supplements: Dietary Fibre.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.