Calculate net carbs by subtracting fibre and half of sugar alcohols from total carbohydrate.
Usage Tip
Use the nutrition label total carbs, then subtract the listed fibre.
What Are Net Carbs?
Net carbs are the carbohydrates your body actually digests into glucose. Fibre and most sugar alcohols pass through largely unabsorbed, so they are subtracted from the total. The result is the number low-carb and keto eaters track.
Allulose, a rare sugar, is also subtracted because it is not metabolised for energy. The calculator above does the subtraction and lets you choose how much of the sugar alcohols to count.
Net Carbs vs Total Carbs
Total carbs is everything on the label – starches, sugars, fibre, and sugar alcohols. Net carbs removes the parts that do not raise blood sugar much. For ketosis and blood-sugar management, net carbs are the practical number; for strict tracking or certain medical situations, total carbs still matter.
Fibre & Sugar Alcohols
Fibre is a carbohydrate the body cannot digest, so it is fully subtracted. Sugar alcohols vary: some (erythritol, allulose) have almost no blood-sugar impact and are subtracted fully; others (maltitol, sorbitol) are partly absorbed, so many people subtract only half.
| Sweetener | Blood-sugar impact | Commonly subtracted |
|---|---|---|
| Erythritol | Negligible | 100% |
| Allulose | Negligible | 100% |
| Xylitol | Low-moderate | ~50% |
| Sorbitol | Moderate | ~50% |
| Maltitol | Higher | ~50% or less |
| Isomalt | Moderate | ~50% |
Net Carbs on Keto
Keto runs on net carbs – typically under 20 g per day for strict keto, up to about 50 g for more relaxed low-carb. Because fibre is free, high-fibre vegetables and nuts fit easily, while the same total-carb count from bread or sugar would blow the budget. Use the keto mode to subtract sugar alcohols fully.
Diabetes & Carb Counting
For diabetes management, guidance often differs: subtract fibre only when it exceeds about 5 g per serving, and count only half of sugar alcohols, since some still raise blood glucose. The diabetic mode applies the more conservative half-subtraction. Always follow your own care team’s plan.
Common Food Net Carb Examples
| Food | Total carbs | Fibre | Net carbs |
|---|---|---|---|
| 1/2 avocado | 9 g | 7 g | 2 g |
| 1 oz almonds | 6 g | 3.5 g | ~2.5 g |
| 1 cup broccoli | 6 g | 2.4 g | ~3.6 g |
| Low-carb tortilla | 18 g | 12 g | ~6 g |
| Protein bar (with sugar alcohols) | 24 g | 10 g | ~6–10 g |
Naturally Low-Carb Foods
- Meat, poultry, fish, eggs (essentially 0 net carbs)
- Leafy greens, broccoli, cauliflower, zucchini, peppers
- Avocado, olives
- Nuts and seeds (in moderation)
- Cheese and full-fat dairy
Reading a Nutrition Label for Net Carbs
Find Total Carbohydrate, then look beneath it for Dietary Fibre and, if listed, Sugar Alcohols (often under “Sugars” or in the ingredients). Subtract fibre and the sugar alcohols you count. Watch serving sizes – the label is per serving, and packages often contain several.
Common Mistakes
- Forgetting to multiply by the number of servings in the package.
- Subtracting 100% of every sugar alcohol – maltitol still raises blood sugar.
- Counting added fibre (some isolated fibres are partly digestible).
- Ignoring total carbs entirely when a medical plan calls for them.
- Trusting “net carb” claims on packaging without checking the math.
Frequently Asked Questions
How do you calculate net carbs?
Subtract fibre and sugar alcohols from total carbohydrate: Net Carbs = Total − Fibre − Sugar Alcohols. Allulose is also subtracted.
Do you subtract all sugar alcohols?
Not always. Erythritol and allulose are subtracted fully; maltitol, sorbitol, and xylitol are often only half-subtracted because they partly raise blood sugar.
What are net carbs on keto?
The carbs that count toward your daily limit – usually under 20 g for strict keto, up to ~50 g for relaxed low-carb.
Should diabetics use net or total carbs?
Many plans count total carbs or subtract only fibre over 5 g and half of sugar alcohols. Follow your care team; the diabetic mode here is conservative.
Is allulose a net carb?
No – allulose is not metabolised for energy, so it is subtracted like fibre.
Are net carbs an official measurement?
No. “Net carbs” is not regulated or standardised, so methods vary. Total carbohydrate is the only figure required on labels.
Related Keto Calculators
Note: net carbs are not a standardised or regulated measurement – methods differ, and sugar alcohols affect people differently. Total carbohydrate remains useful, especially for diabetes. This tool is for general information and label math, not medical or dietary advice; if you manage diabetes or another condition, follow your healthcare provider’s guidance.