Net Carbs Calculator
HealthTrack net carbs for keto and low-carb diets by subtracting fiber and sugar alcohols from total carbohydrates. Get instant, accurate results per serving.
Net Carbs
25
Fiber + Sugar Alcohols Subtracted
5
What is a Net Carbs?
A Net Carbs Calculator finds the carbohydrate grams in a food that actually impact blood sugar and ketosis, by subtracting dietary fiber and sugar alcohols from total carbohydrates. It's the standard math behind the "net carbs" figure printed on many keto and low-carb product labels, and it matters because the FDA's mandatory Nutrition Facts panel only lists total carbohydrates — it doesn't calculate net carbs for you.
The concept exists because not all carbohydrates behave the same way in the body. Starches and sugars are broken down into glucose and absorbed into the bloodstream, while dietary fiber largely passes through undigested and many sugar alcohols (like erythritol, xylitol, and maltitol) are only partially metabolized. For someone following a ketogenic diet — where staying under a daily carb ceiling (often 20–50g) is the whole point — total carbohydrate figures can be misleading if a food is high in fiber or sugar alcohols. This calculator applies the widely used formula: net carbs = total carbs − fiber − sugar alcohols, giving a more useful number for day-to-day tracking. Pair it with a Macro Calculator to see how your carb intake fits into your overall daily macros.
How to use this Net Carbs calculator
- Find the Nutrition Facts panel on the food label or packaging you want to check.
- Enter the Total Carbohydrates value from the label into the calculator, in grams per serving.
- Enter the Dietary Fiber value from the same label into the Dietary Fiber field, in grams.
- Enter the Sugar Alcohols value if listed on the label (sometimes shown as "sugar alcohol" or a specific type like erythritol) into the Sugar Alcohols field; enter 0 if none is listed.
- Review the Net Carbs result, shown as the highlighted primary output in grams per serving.
- Check the Fiber + Sugar Alcohols Subtracted secondary output to see how much of the total carbohydrate count was excluded from the net figure.
- Use the calculated net carbs value to log the food against your daily keto or low-carb carbohydrate target.
Formula & Methodology
The calculator applies the standard net carbs formula used across the low-carb and keto community: Net Carbs = Total Carbohydrates − Dietary Fiber − Sugar Alcohols Where: - Total Carbohydrates is the full carbohydrate figure from the Nutrition Facts label, in grams - Dietary Fiber is the fiber grams listed under Total Carbohydrates on the same label - Sugar Alcohols is the sugar alcohol grams listed on the label, if present (e.g. erythritol, xylitol, maltitol) Worked example: A protein bar lists 22g Total Carbohydrates, 9g Dietary Fiber, and 8g Sugar Alcohols (erythritol) per serving. Net Carbs = 22 − 9 − 8 = 5g net carbs per serving Note that this calculator uses the full subtraction convention. Some brands and tracking apps use variant methods — for example, excluding erythritol entirely from the subtraction (since it has near-zero glycemic impact) or counting only half the grams of other sugar alcohols like maltitol. If a packaged food's printed "net carbs" claim differs from this calculator's result, it likely reflects one of these alternate conventions rather than an error in either calculation. For a fuller definition, see our glossary entry on Net Carbs.
Frequently Asked Questions
Net carbs are calculated as total carbohydrates minus dietary fiber minus sugar alcohols. This formula reflects the carbohydrate content that has a meaningful impact on blood sugar, since fiber and most sugar alcohols are not fully broken down and absorbed the way starches and sugars are.
Fiber passes through the digestive system largely intact and is not converted into glucose, so it does not raise blood sugar the way digestible carbohydrates do. Subtracting it gives a more accurate picture of the carbs your body actually metabolizes for energy.
No, sugar alcohols vary widely in how much they affect blood sugar. Erythritol is largely excreted unchanged and has almost zero glycemic impact, while maltitol is partially absorbed and can raise blood sugar meaningfully, so some trackers exclude erythritol entirely or count only half of other sugar alcohols.
Total carbs is the full carbohydrate count on a nutrition label, including starches, sugars, fiber, and sugar alcohols. Net carbs is a subset of that figure, total carbs minus fiber and sugar alcohols, used mainly by people following ketogenic or low-carb diets to track carbohydrates that meaningfully affect blood sugar and ketosis.
No, the FDA does not require or officially define net carbs on nutrition labels, and total carbohydrate is the only figure mandated on the Nutrition Facts panel. The net carbs convention was popularized by the low-carb and keto community as a practical way to estimate carbohydrate impact, so calculation methods can vary slightly between brands and apps.
Enter the Total Carbohydrates, Dietary Fiber, and Sugar Alcohols values from a food label, all in grams per serving. The calculator instantly subtracts the fiber and sugar alcohols from the total and displays your net carbs per serving.
Mathematically it is possible if fiber and sugar alcohols add up to more than total carbs, which can happen with heavily fortified low-carb products. This calculator floors the result at zero grams, since a food cannot realistically have negative net carbs.
Most standard ketogenic diets target roughly 20 to 50 grams of net carbs per day to maintain ketosis, though the exact number depends on individual metabolism, activity level, and goals. Tracking net carbs per serving with this calculator makes it easier to add up your daily total across meals.
Yes, net carbs is commonly used across various low-carb approaches, including Atkins, low-carb Mediterranean-style eating, and general carb-conscious diets, not exclusively ketogenic ones. The core idea of subtracting carbs that do not meaningfully affect blood sugar is useful anytime you are tracking carbohydrate intake for metabolic reasons.
Some manufacturers pre-calculate net carbs on their packaging using their own formula, which may exclude erythritol entirely or discount only half of certain sugar alcohols rather than subtracting the full amount. This calculator uses the standard total-minus-fiber-minus-sugar-alcohols formula, so results can differ slightly from a brand's proprietary net carbs claim.
If you are not specifically managing ketosis or blood sugar response, tracking total carbohydrates alongside overall calories and macros is usually sufficient. Net carbs becomes most useful when fiber and sugar alcohols make up a meaningful share of a food's total carbohydrate count, such as with protein bars or keto-labeled products.
Fiber supports digestive health and satiety and is generally something to increase rather than restrict, even on a low-carb diet; it is simply excluded from net carbs because of its minimal blood sugar impact. Pairing net carbs tracking with a daily calorie and protein target helps you keep fiber-rich, low-net-carb foods within your broader nutrition goals.
Also known as