Counting carbs on keto? This free net carb calculator subtracts fiber and sugar alcohols from total carbs to show the digestible carbs that count toward your daily limit.
Net carbs are the carbs your body digests for energy. Fiber and most sugar alcohols pass through with little blood-sugar impact, so they’re subtracted from total carbs.
A guide for low-carb and keto eating. Practices vary — some count all sugar alcohols, others half (erythritol is often fully subtracted). Use whichever your plan follows, and check with a professional for medical conditions like diabetes.
How the Net Carb Calculator Works
Net carbs estimate the carbohydrate grams your body actually digests and converts toward blood sugar, by removing fiber and sugar alcohols from the total carbohydrate on a nutrition label. This calculator applies that subtraction directly from the numbers you enter.
Formula: Net Carbs = Total Carbohydrate − Dietary Fiber − Sugar Alcohols (subtracted in full or at half, whichever mode you choose), floored at 0. Net Carb Calories = Net Carbs × 4 kcal/g.
- Total carbohydrate — total carb grams from the nutrition label
- Dietary fiber — fiber grams from the label; always subtracted in full
- Sugar alcohols — grams of sugar alcohols such as erythritol or maltitol, if listed
- Sugar alcohol mode — whether to subtract all sugar alcohol grams or only half, since keto and low-carb plans differ on this
Example Scenarios
| Total Carbs (g) | Fiber (g) | Sugar Alcohols (g) | SA Mode | Net Carbs (g) |
|---|---|---|---|---|
| 30 | 8 | 0 | Subtract all | 22 |
| 45 | 5 | 10 | Subtract all | 30 |
| 20 | 3 | 6 | Subtract half | 14 |
| 60 | 0 | 20 | Subtract all | 40 |
| 25 | 4 | 8 | Subtract half | 17 |
| 10 | 12 | 0 | Subtract all | 0 |
Net Carb Calculator FAQ
Should I subtract all sugar alcohols or just half?
Many keto plans subtract erythritol in full since it has minimal blood-sugar impact, but subtract other sugar alcohols like maltitol at half since they affect blood sugar more. Check the rule your specific diet plan follows and stay consistent so your tracking stays comparable day to day.Why do net carbs matter more than total carbs on keto?
Keto focuses on limiting carbs that actually raise blood sugar and insulin. Fiber and many sugar alcohols pass through digestion largely unmetabolized, so subtracting them from total carbohydrate gives a closer estimate of the carbs your body converts to glucose.Can net carbs ever be a negative number?
No, this calculator floors net carbs at zero. If fiber and sugar alcohols add up to more than total carbohydrate, the true net carb count is effectively zero even though the raw subtraction might otherwise go negative.What if a food has no sugar alcohols listed?
Leave that field blank or at zero. The calculator will simply subtract dietary fiber from total carbohydrate to give you the net carbs, with no sugar alcohol adjustment involved.Is counting net carbs the same as counting calories?
No, net carbs measure digestible carbohydrate grams, not calories. This tool also shows an estimated net carb calorie figure (net carbs times 4 kcal per gram) as a side reference, but it does not account for calories from protein or fat.Is "net carbs" an official nutrition label term?
No, net carbs are not a term regulated on official nutrition labels. It is shorthand used by low-carb and keto communities to estimate digestible carbohydrate, so exact definitions and subtraction methods can vary between brands and diet plans.Related Calculators
If you're building out a full low-carb meal plan, pair this tool with the keto macro calculator to set your daily fat, protein and carb targets, check whether a food's carbs will spike blood sugar with the glycemic load calculator, or make sure you're still getting enough roughage with the fiber intake calculator.