Net Carbs Calculator
Work out net carbs from total carbohydrate, fiber and sugar alcohols for keto and low-carb tracking.
How it works
net carbs = total carbs − fiber − (sugar alcohols ÷ 2)
Net carbs estimate the carbohydrate that actually raises blood sugar. Fiber is subtracted in full because it is not digested for energy. Most sugar alcohols are only partly absorbed, so a common convention subtracts half of them (erythritol, which is nearly all excreted, is often subtracted in full). This is an informal metric, not an official nutrition label figure.
Worked example
A bar with 30 g total carbs, 8 g fiber and 5 g sugar alcohols: 30 − 8 − (5 ÷ 2) = 30 − 8 − 2.5 = 19.5 g net carbs.
Sources: FDA — How to Understand and Use the Nutrition Facts Label
Frequently asked questions
What are net carbs?
An estimate of the digestible carbohydrate that affects blood sugar, found by subtracting fiber and part of any sugar alcohols from total carbohydrate. It is popular in keto and low-carb diets but is not a regulated nutrition-label value.
Why subtract only half the sugar alcohols?
Most sugar alcohols are partially absorbed and provide some calories and glucose response, so a common rule subtracts half. Erythritol is the exception — it is almost entirely unabsorbed and is often subtracted fully.
Do net carbs matter on keto?
Many keto dieters track net carbs to stay under a daily threshold (often 20–50 g). Others count total carbs to be conservative, since individual responses to fiber and sugar alcohols vary.
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Educational estimate, not medical or dietary advice.