A net carbs calculator for US and UK labels
This net carbs calculator works out the carbohydrate that counts on a keto or low-carb diet: total carbohydrate minus dietary fibre and some or all of the sugar alcohols. Type the numbers from a nutrition label, choose the sweetener, and you get net carbs per serving with the working shown.
It handles the detail most calculators skip. US and Canadian labels include fibre inside “Total Carbohydrate”, but UK and EU labels list fibre separately and have already left it out — subtracting it again under-counts your carbs. The calculator also covers about 300 everyday foods from USDA data, from avocado and paneer to roti and rice, and keeps a running total for the day.
How to use the Net Carbs Calculator
- Choose the Label style: US/Canada if fibre is indented under Total Carbohydrate, UK/EU if fibre has its own line below carbohydrate.
- Enter the carbohydrate, fibre and sugar alcohols / polyols per serving, and pick the sweetener named in the ingredients.
- Set Servings eaten and read the net carbs. Press Add to today to log it.
- For fresh food, search Look up a food, choose a portion and press Add to today.
- Set your Daily net-carb limit to see what is left.
Net Carbs Calculator features
US and UK/EU labels
Applies the right formula for each label style, so fibre is never subtracted twice.
Sugar alcohol rules
Erythritol and allulose are subtracted in full, maltitol, xylitol, sorbitol and isomalt by half, or none if you prefer the strictest count.
300 USDA foods
Household portions and grams, with carbs, fibre and sugars from USDA FoodData Central.
Day total
Foods and label items in one list, with what is left of your limit.
Shows the sum
Every result prints the subtraction, and a bar splits net carbs, fibre and the subtracted sugar alcohol.
The net carbs formula
US-style label: net carbs = total carbohydrate − dietary fibre − sugar alcohols × factor. A bar with 24 g total carbohydrate, 9 g fibre and 8 g erythritol: 24 − 9 − 8 = 7 g. Sweetened with maltitol instead, only half the 8 g is subtracted: 24 − 9 − 4 = 11 g.
UK/EU-style label: under Regulation (EU) No 1169/2011, which the UK kept, “carbohydrate” means carbohydrate that is metabolised by humans and includes polyols, while fibre is a separate nutrient. So net carbs = carbohydrate − polyols × factor. The same bar sold in the UK would show about 15 g carbohydrate; 15 − 8 = 7 g, the same answer.
Why sweeteners are treated differently
Sugar alcohols are only partly absorbed, and the share varies. Erythritol is largely excreted unchanged — EU labelling counts it as 0 kcal per gram, against 2.4 for other polyols — so it is subtracted in full. Allulose is a rare sugar: the US FDA’s October 2020 guidance lets makers leave it out of “Total Sugars” and count 0.4 kcal per gram, but it still sits inside Total Carbohydrate, so it is subtracted too. For maltitol, sorbitol, xylitol and isomalt, subtracting half is the usual compromise; choose “Subtract none” if they raise your blood glucose.
| Sweetener | Subtracted here | Note |
|---|---|---|
| Erythritol | All | 0 kcal/g on EU labels |
| Allulose | All | 0.4 kcal/g (FDA, 2020) |
| Xylitol, sorbitol, isomalt | Half | Partly absorbed |
| Maltitol | Half | Partly absorbed; some people count it in full |
| Sugar, honey, dextrose | None | These are sugars, not sugar alcohols |
Tips for counting
- Check the ingredients for the polyol name — many labels show only “sugar alcohols” or “polyols”.
- USDA values for fresh foods are averages; a packaged food’s own label is better when you have it.
- Plan protein and fat with the macro calculator, and check calories with the food calorie calculator.
Net Carbs Calculator FAQ
How do I calculate net carbs?
On a US label, subtract fibre and sugar alcohols (all of erythritol and allulose, about half of most others) from Total Carbohydrate. On a UK or EU label, subtract only the polyols, because fibre is already excluded. The net carbs calculator does either.
Do UK food labels show net carbs?
In effect, mostly yes: UK and EU “carbohydrate” already excludes fibre. Only polyols, if listed, need subtracting. Never subtract the fibre line on a UK label.
Is erythritol zero net carbs?
It is normally subtracted in full because the body absorbs it but does not metabolise it for energy; EU rules give it 0 kcal per gram.
How many net carbs a day is keto?
Many keto plans use roughly 20–50 g of net carbs a day, but needs differ. Set your own limit in the calculator, and get advice if you have a medical condition.
Is there a net carbs calculator app?
This page works like an app on your phone: no install or sign-up, and your day list is saved in your browser. Add it to your home screen for one-tap access.
Is net carbs an official label term?
No. US and UK/EU labelling rules do not define “net carbs”, so brands calculate it differently. Working it out yourself from the label is more reliable.