Net Carbs Calculator – Calculate Net Carbs for Keto & Low-Carb

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

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 build a full keto meal plan or low-carb meal plan within your net carb budget.