Net carbs are the carbohydrates your body actually digests and uses for energy. They're calculated by subtracting fiber and certain sugar alcohols from total carbs. On keto and low-carb diets, tracking net carbs gives a more accurate picture of how food affects your blood sugar and ketosis.
Net Carbs Calculator – Calculate Net Carbs for Keto & Low-Carb
Calculate net carbs instantly. Enter total carbs, fiber, and sugar alcohols to find your net carb count. Essential for keto and low-carb diets.
What are net carbs?
Net carbs are the carbohydrates your body actually digests and converts to glucose. They're calculated by subtracting fiber and certain sugar alcohols from total carbohydrates. On keto, low-carb, and diabetic diets, tracking net carbs gives a more accurate picture of how food affects your blood sugar and insulin response than total carbs alone.
How to calculate net carbs
The basic formula is simple:
- Net Carbs = Total Carbs − Fiber − Sugar Alcohols (adjusted)
- Fiber is fully subtracted because your body can't digest it into glucose.
- Sugar alcohols are partially subtracted depending on their type. Erythritol has zero glycemic impact (subtract 100%), while maltitol and sorbitol are about 50% absorbed (subtract only 50%).
For example: a protein bar with 25 g total carbs, 10 g fiber, and 5 g erythritol has 10 g net carbs (25 − 10 − 5 = 10). But if those 5 g were maltitol instead, the net carbs would be 12.5 g (25 − 10 − 2.5 = 12.5).
Why do net carbs matter for keto?
On a ketogenic diet, your body switches from burning glucose to burning fat (ketones) for energy. This metabolic state — called ketosis — is maintained by keeping carb intake very low. But not all carbs affect ketosis equally. Fiber passes through your gut without being converted to glucose, so it doesn't spike insulin or knock you out of ketosis. That's why most keto practitioners track net carbs (typically 20–25 g per day) rather than total carbs.
Not all sugar alcohols are equal
Sugar alcohols are used as low-calorie sweeteners in many "sugar-free" and "keto-friendly" products. But their glycemic impact varies dramatically:
- Erythritol (0% impact): Almost completely excreted unchanged. No effect on blood sugar or ketosis. The gold standard for keto sweeteners.
- Xylitol (40% impact): Partially absorbed. Lower glycemic index than sugar but can cause digestive issues in large amounts.
- Sorbitol (50% impact): About half is absorbed. Common in sugar-free candies and gums. Can cause bloating and diarrhea.
- Maltitol (50% impact): Significantly raises blood sugar — almost as much as regular sugar. Many "keto" products use maltitol; check labels carefully.
- Isomalt (50% impact): About half is absorbed. Often used in sugar-free chocolate and baked goods.
Pro tip: If a "keto" product uses maltitol, its actual net carb count is much higher than advertised. Always check which sugar alcohol is used, not just the total amount.
Reading nutrition labels for net carbs
How you calculate net carbs depends on where the product was made:
- US/Canada labels: "Total Carbohydrates" includes fiber and sugar alcohols. Subtract them:
Net = Total Carbs − Fiber − Sugar Alcohols. - EU/UK/Australia labels: "Carbohydrates" on these labels typically already excludes fiber. You may only need to subtract sugar alcohols:
Net = Carbohydrates − Sugar Alcohols.
Always look under "Total Carbohydrates" for the sub-listings of Dietary Fiber and Sugar Alcohols. If sugar alcohols aren't listed but the ingredients include erythritol, xylitol, or similar, the label may already exclude them in some regions.
How many net carbs per day?
Your daily net carb target depends on your diet approach:
- Strict keto: Under 20 g net carbs/day. Best for rapid ketosis induction and therapeutic ketogenic diets.
- Standard keto: 20–25 g net carbs/day. Most common target that works for the majority of people.
- Liberal low-carb: 25–50 g net carbs/day. May allow ketosis for active individuals but isn't guaranteed.
- Moderate low-carb: 50–100 g net carbs/day. Not typically ketogenic but still lower than standard diets (~250–300 g).
Common high-fiber, low-net-carb foods
These foods are your best friends on a keto or low-carb diet:
- Avocado (1 medium): 12 g total carbs, 10 g fiber = 2 g net carbs
- Raspberries (100 g): 12 g total carbs, 6.5 g fiber = 5.5 g net carbs
- Chia seeds (2 tbsp): 12 g total carbs, 10 g fiber = 2 g net carbs
- Broccoli (100 g): 6 g total carbs, 2.6 g fiber = 3.4 g net carbs
- Almond flour (¼ cup): 6 g total carbs, 3 g fiber = 3 g net carbs
- Cauliflower (100 g): 5 g total carbs, 2 g fiber = 3 g net carbs
How this calculator works
Enter total carbs, fiber, and sugar alcohols for any food. Select the sugar alcohol type to apply the correct absorption factor (0–50%). The calculator shows your net carb count and how it fits within your daily keto budget (20 g, 25 g, or 50 g).
Bottom line
Net carbs give you a more accurate view of how food affects your body:
- Fiber doesn't raise blood sugar — subtract it
- Sugar alcohol impact varies — erythritol is safe, maltitol is not
- Most people maintain ketosis at 20–25 g net carbs/day
- Check which sugar alcohol is used, not just the amount
Use this calculator to check foods and recipes, then let AI Meal Planner build a full keto or low-carb meal plan within your net carb budget.
Create Your Keto Meal Plan
Personalized low-carb meals within your net carb budget. Free to start.
Frequently Asked Questions
Most people stay in ketosis with 20–25g of net carbs per day. Some can tolerate up to 50g, especially if they're very active. Strict keto typically targets under 20g, while a more relaxed low-carb approach allows 25–50g. Start at 20g and adjust based on how your body responds.
No. Erythritol has virtually zero glycemic impact and can be fully subtracted. Others like maltitol, sorbitol, and xylitol are partially absorbed (40–50%), so only a portion is subtracted. This calculator lets you choose the sugar alcohol type to get an accurate net carb count.
Fiber is technically a carbohydrate, but your body can't digest it into glucose. Soluble fiber may produce a small amount of energy through fermentation in the gut, but it doesn't raise blood sugar like starch or sugar. That's why it's fully subtracted when calculating net carbs.
In the US, fiber and sugar alcohols are already included in Total Carbohydrates on the label. Subtract Dietary Fiber and Sugar Alcohols (adjusting for type) from Total Carbohydrates to get net carbs. In the EU and UK, labels often show "Carbohydrates" which already excludes fiber — so that number is closer to net carbs.