Net Carbs Calculator

Net carbs = Total Carbs − Fiber − (Sugar Alcohols × absorption factor). Fiber is completely subtracted because your body cannot digest it. Sugar alcohols are partially subtracted based on their glycemic impact — erythritol is fully subtracted (0% absorption), while maltitol, sorbitol, and isomalt are only half subtracted (50% absorption), and xylitol is 40% subtracted (60% absorption).

Net carbs are the carbohydrates that your body actually digests and uses for energy, raising blood sugar and insulin levels. On a ketogenic diet, keeping net carbs between 20–50g per day forces your body to burn fat for fuel instead of glucose. Tracking net carbs rather than total carbs gives a more accurate picture of the carbs that affect ketosis.

Most people enter and maintain ketosis by eating 20–25g of net carbs per day. Some metabolically flexible individuals can stay in ketosis with up to 50g per day, especially if they are physically active. Beginners should start with 20g per day for the first 2–4 weeks, then gradually experiment with higher amounts while monitoring ketone levels.

No. Sugar alcohols vary significantly in how much they raise blood sugar. Erythritol has virtually zero glycemic impact and zero calories — it passes through the body unabsorbed. Maltitol has about 50% of the glycemic impact of regular sugar and can spike blood sugar. Xylitol falls in between at about 60% absorption. Always check which sugar alcohol is used in "sugar-free" products.

In the US, nutrition labels include fiber in total carbohydrates, so you subtract all fiber to get net carbs. In Europe, UK, and Australia, fiber is already excluded from the carbohydrate count on labels, so the listed carbs are effectively net carbs — do not subtract fiber again or you'll undercount.

The lowest net carb foods include leafy greens (spinach 0.4g, lettuce 0.6g per cup), non-starchy vegetables (celery 0.8g, cucumber 1g per cup), meats and fish (0g), eggs (0.4g each), cheese (0.4–1g per oz), and healthy fats like butter and olive oil (0g). High-fiber vegetables like broccoli and cauliflower are also excellent because much of their carb content is indigestible fiber.

No. Fiber does not raise blood sugar or insulin levels because your body cannot break it down into glucose. You can eat high-fiber foods freely on keto without worrying about ketosis. In fact, fiber is encouraged on keto for digestive health. Aim for 25–30g of fiber per day from low-carb vegetables, nuts, and seeds.

US nutrition labels list total carbohydrates including fiber, so you must subtract fiber to get net carbs. European and UK labels list "carbohydrates" with fiber already excluded — the number shown is effectively net carbs. If you're using European products, the carb count on the label is already your net carb count.