Net Carbs Calculator
Calculate net carbs from total carbohydrates, fiber, and sugar alcohols.
Net Carbs
grams
Breakdown
What Are Net Carbs?
Net carbs (sometimes called "digestible" or "impact" carbs) represent the carbohydrates in a food that your body actually digests and absorbs as glucose, raising blood sugar. They are calculated by subtracting components that have little or no impact on blood sugar – primarily dietary fiber and, in part, sugar alcohols – from the total carbohydrate count.
Net Carbs = Total Carbs − Fiber − (Sugar Alcohols ÷ 2)
For example, a food with 20 g total carbs, 8 g fiber, and 4 g sugar alcohols has 20 − 8 − 2 = 10 g net carbs. The result is clamped to a minimum of 0 g.
Total vs. Net Carbs: US vs. EU Labeling
How you read a nutrition label depends on where the food was produced, because the two major labeling systems count carbohydrates differently:
- United States (and Canada): The "Total Carbohydrate" figure includes dietary fiber and sugar alcohols. To get net carbs you must subtract them yourself.
- European Union (and much of the world): The "Carbohydrate" figure already excludes fiber, which is listed separately. In effect, EU labels are closer to net carbs, but you may still need to subtract sugar alcohols (polyols).
This calculator follows the US convention: enter the total carbohydrate value and the fiber and sugar alcohols you want to subtract from it.
Fiber and Sugar Alcohols
Dietary fiber is a carbohydrate that the human body cannot break down for energy. Because it passes through largely undigested, it does not raise blood glucose and is fully subtracted when calculating net carbs.
Sugar alcohols (polyols such as erythritol, xylitol, maltitol, and sorbitol) are partially absorbed. The widely used convention is to subtract half of the sugar alcohol grams, because on average they contribute roughly half the glycemic impact of regular carbohydrates.
There is an important nuance: erythritol is almost entirely excreted unchanged and has essentially no glycemic impact, so in practice many people subtract it in full. Maltitol, by contrast, raises blood sugar significantly and is sometimes counted almost like a regular carb. This calculator applies the standard half-subtraction for simplicity; adjust the result if your sugar alcohol is predominantly erythritol (subtract fully) or maltitol (subtract less).
Net Carbs and the Keto Diet
On a ketogenic diet, the goal is to keep carbohydrate intake low enough to enter and stay in ketosis – a metabolic state in which the body burns fat for fuel. Most keto plans target 20–50 g of net carbs per day. Because fiber and (partly) sugar alcohols have a minimal effect on blood sugar and insulin, counting net carbs rather than total carbs allows for a more flexible, food-rich diet that still supports ketosis.
- Strict keto: often under 20 g net carbs/day for rapid or reliable ketosis.
- Moderate / standard keto: 20–50 g net carbs/day suits most people.
- Be cautious with labels: some "keto" or "low-carb" products inflate their net-carb claims by subtracting sugar alcohols such as maltitol in full, which can still spike blood sugar.
Note: The concept of net carbs is not officially defined or regulated by the FDA or most other authorities. Individual responses to fiber and sugar alcohols vary. These estimates are for informational purposes only and should not replace advice from a qualified healthcare professional or registered dietitian, especially if you manage diabetes or another metabolic condition.