Net Carbs Calculator
Add up net carbs from nutrition labels by subtracting fibre and sugar alcohols, with erythritol excluded, and track the day's total against your carb limit.
Foods (from the nutrition label)
Net carbs: 4.0 g per serving · 4.0 g for the servings entered
Net carbs: 9.0 g per serving · 9.0 g for the servings entered
Net carbs: 11.0 g per serving · 11.0 g for the servings entered
Net carbs by food
| Food | Servings | Carbs | Fibre | Sugar alcohols | Net / serving | Net total |
|---|---|---|---|---|---|---|
| Keto bread, 2 slices | 1.0 | 12.0 g | 8.0 g | 0.0 g | 4.0 g | 4.0 g |
| Greek yogurt, 170 g | 1.0 | 9.0 g | 0.0 g | 0.0 g | 9.0 g | 9.0 g |
| Protein bar | 1.0 | 22.0 g | 9.0 g | 8.0 g (4.0 g erythritol) | 11.0 g | 11.0 g |
| Day total | 43.0 g | 17.0 g | 24.0 g |
Net carbs = total carbohydrate − dietary fibre − sugar alcohols (counted at half, with erythritol removed first). Each deduction is a checkbox above, so you can match whichever convention your plan uses. A food never goes below 0 g net carbs.
You have 1.0 g of net carbs left today.
Label arithmetic only — this is an estimate, not medical or nutritional advice, and it diagnoses nothing. “Net carbs” is a marketing convention, not a regulated term: neither the FDA nor the EU defines it, and individual sugar alcohols raise blood glucose by very different amounts (erythritol barely at all, maltitol substantially). If you take insulin or another glucose-lowering medication, dose from your meter and your clinician's advice, never from a web calculator.
What is the Net Carbs Calculator?
Net carbs are total carbohydrate minus dietary fibre and minus sugar alcohols, which are usually counted at half their grams with erythritol excluded entirely. The result estimates the carbohydrate that actually reaches your bloodstream.
- Per-serving and per-day net carbs across an unlimited food list
- Three toggles: subtract fibre, halve sugar alcohols, exclude erythritol
- Live progress bar against your own daily limit, turning red when you go over
- Never returns a negative net carb figure, and flags labels that do not add up
- Full breakdown table showing carbs, fibre and sugar alcohols alongside the net figure
- 100% local — your food diary never leaves the browser
How to use the Net Carbs Calculator
- 1
Set your daily net carb limit — 20 to 30 g for strict keto, 50 to 100 g for a general low-carb plan.
- 2
Tick or untick the three deduction rules so they match the convention your plan and your food labels use.
- 3
For each food, enter its name, the servings you ate, and the total carbohydrate, fibre, sugar alcohol and erythritol grams from the label.
- 4
Use Add food to build up the whole day, and the bin icon to remove anything you did not eat.
- 5
Read the per-food net carbs, the day total and the progress bar showing how much of your limit is left.
About the Net Carbs Calculator
The ByteTools Net Carbs Calculator does the label arithmetic that keto and low-carb plans depend on. Enter the total carbohydrate, fibre and sugar alcohol figures from each food's nutrition panel, add how many servings you ate, and it shows the net carbs per serving, the total for the day, and how much of your daily limit is left.
Every deduction is a checkbox, because the conventions genuinely differ. US labels list total carbohydrate including fibre, so fibre is subtracted; UK and EU labels already exclude it, so you can switch that off. Sugar alcohols are counted at half their grams by default, with erythritol removed first since it is absorbed and excreted almost unchanged.
All the arithmetic happens locally in your browser — no food diary is uploaded, saved or shared. This is label maths, not medical or nutritional advice, and it does not diagnose or manage any condition. If you take insulin or another glucose-lowering medication, work from your meter and your clinician's advice rather than a web calculator.
Frequently asked questions
How do you calculate net carbs?
Take the total carbohydrate on the label, subtract the dietary fibre, then subtract the sugar alcohols — usually only half of them, and skipping erythritol entirely. So a bar with 22 g total carbs, 9 g fibre and 8 g sugar alcohols of which 4 g is erythritol comes out at 22 − 9 − 2 = 11 g net carbs.
Why is erythritol not counted at all?
Erythritol is absorbed in the small intestine and excreted in urine largely unchanged, so it contributes essentially no calories and has a negligible effect on blood glucose or insulin. Other sugar alcohols such as maltitol behave quite differently and do raise glucose, which is why the calculator counts them at half by default.
Do I subtract fibre on UK or EU labels?
No. European labels list carbohydrate with fibre already excluded, so subtracting it again double counts. Untick the fibre checkbox when you are reading an EU, UK or Australian label, and leave it on for a US nutrition facts panel.
How many net carbs a day is ketogenic?
Most ketogenic protocols aim for 20 to 30 g of net carbs a day, and many people find they stay in ketosis somewhat above that. Lower-carb but non-ketogenic plans usually sit between 50 and 130 g. Set whichever figure your plan uses as the limit and the progress bar will track it.
Is net carbs an official term?
No, and that matters. Neither the US FDA nor EU food law defines or regulates “net carbs” — it is a manufacturer and diet-community convention. That is why this tool lets you choose each deduction rather than baking one interpretation in.
Is my food data private?
Completely. The calculator is plain JavaScript running in your browser; nothing you enter is uploaded, stored or sent anywhere, and the page keeps working with no network connection.
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