Net Carbs Calculator

Net carbs are the carbohydrates that your body actually digests and uses for energy. They are calculated by subtracting fiber and sugar alcohols from total carbohydrates. Total carbs include all carbohydrate types -- sugars, starches, fiber, and sugar alcohols. Since fiber and most sugar alcohols do not significantly raise blood sugar, subtracting them gives a more accurate picture of a food's glycemic impact. This distinction is especially important for keto, low-carb, and diabetic diets.

Most ketogenic diet guidelines recommend consuming 20 to 50 grams of net carbs per day. For strict keto and guaranteed ketosis, staying under 20 grams is the safest target. Some physically active individuals may tolerate up to 50 grams and still remain in ketosis. Start at 20 grams, monitor your ketone levels (via urine strips or a blood meter), and gradually adjust upward if desired. Individual carb tolerance varies based on activity level, muscle mass, and metabolic health.

It depends on the type of sugar alcohol. Erythritol has a glycemic index of zero and can be fully subtracted. However, maltitol (GI ~36), sorbitol (GI ~9), and xylitol (GI ~7) are partially absorbed and may affect blood sugar. A conservative approach is to subtract erythritol completely but only subtract half the grams of other sugar alcohols. This calculator subtracts all sugar alcohols by default -- the standard US FDA approach -- but you can manually adjust the input if you prefer a more conservative count.

In the United States, total carbohydrates on the nutrition label include fiber and sugar alcohols, so you must subtract them manually to find net carbs. In the European Union and many other countries, the "carbohydrates" line on the label already excludes fiber -- it shows what Americans would call net carbs. If you are reading a European label, the carbohydrate figure is already your net carb count (though you may still want to subtract sugar alcohols if listed separately).

Mathematically, if you enter more fiber and sugar alcohols than total carbs, the formula would produce a negative number. However, this should not happen with accurate nutrition data because fiber and sugar alcohols are subcategories of total carbohydrates. If you get a negative result, double-check your inputs against the food label. Our calculator sets the minimum net carbs to zero in these edge cases to maintain a realistic result.

Yes. Even outside of keto, focusing on net carbs encourages you to eat more fiber-rich foods, which are linked to greater satiety, better digestive health, and more stable blood sugar. High-fiber foods tend to be less calorie-dense and more filling, which naturally supports a calorie deficit. Replacing refined carbs (high net carbs, low fiber) with whole foods (lower net carbs, high fiber) is a universally effective strategy for weight management regardless of your specific diet plan.

Cooking can change the structure of starches in some foods, potentially affecting digestibility. For example, cooking and then cooling potatoes or rice creates resistant starch, which acts more like fiber and lowers the effective net carb count. However, these changes are relatively small and difficult to quantify precisely. For practical purposes, use the net carb values from the nutrition label (which are based on the food as sold or prepared) and focus on total daily consistency rather than micro-optimizing individual items.