What are net carbs?
Net carbs are the carbohydrates your body actually digests for energy. Fiber and most sugar alcohols pass through with little blood-sugar impact, so low-carb and keto eaters subtract them from the total on the label.
How to calculate net carbs
The common formula, which this calculator uses:
- Net carbs = total carbs − fiber − erythritol − (½ × other sugar alcohols)
- Fiber is subtracted in full.
- Erythritol is subtracted in full — it's largely not metabolised.
- Other sugar alcohols (maltitol, sorbitol, xylitol) are subtracted at half, since they partly raise blood sugar.
Swoodie shows net carbs on every meal you scan or log, so you don't have to do this by hand each time. See the keto guide for low-carb meal ideas.
A general nutrition tool for managing carbs — not medical advice.
Frequently asked questions
How do you calculate net carbs?
Subtract fiber and sugar alcohols from total carbs: net carbs = total carbs − fiber − erythritol − (half of other sugar alcohols). This calculator does it for you and shows the working.
Why are sugar alcohols only half-subtracted?
Erythritol is mostly not metabolised, so it's subtracted fully. Other sugar alcohols like maltitol partly raise blood sugar, so the common approach subtracts only half.
Do I subtract all fiber?
Yes — fiber isn't digested for energy, so the full fiber amount is subtracted from total carbs.