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Net Carbs

General

Net Carbohydrates

Total carbohydrate grams minus fiber grams — the figure that matters most for staying in ketosis, since fiber has minimal impact on blood sugar or ketone production.

Definition

Net carbs is the carbohydrate figure used for tracking blood sugar impact and ketosis, calculated by subtracting a food's fiber content from its total carbohydrate content. It's the standard tracking metric for low-carb and ketogenic diets, since fiber passes through the digestive system largely unabsorbed and has little effect on blood sugar or ketone levels.

Nutrition labels list total carbohydrates, but low-carb dieters typically need to do one extra subtraction step to get the net carb figure that actually matters for their diet. Tools like the Net Carbs Calculator perform this subtraction automatically.

Formula

Net Carbs = Total Carbohydrates (g) − Fiber (g)

Some trackers also subtract sugar alcohols:

Net Carbs = Total Carbohydrates (g) − Fiber (g) − Sugar Alcohols (g)

Worked Example

A food label shows 18g total carbohydrates and 7g fiber per serving:

Net Carbs = 18 − 7 = 11g net carbs

This is the figure to log against a daily keto net carb budget (typically 20–50g), not the 18g total carbohydrate figure.

Key Things to Know

  • Fiber-rich foods often have a smaller net carb impact than they appear: don't avoid high-fiber vegetables just because their total carb count looks high.
  • Track against your daily keto budget, not total carbs: consistently using net carbs instead of total carbs is the single biggest factor in staying in ketosis reliably.
  • Sugar alcohol subtraction varies by tracker: some apps and labels subtract all sugar alcohols, others don't — check the specific policy if your numbers seem inconsistent.
  • Pair with a fiber target: because high-carb, high-fiber foods are often restricted on keto, it's easy to under-eat fiber without deliberately tracking it separately.

Related Calculators

Net Carbs Calculator →Track net carbs for keto and low-carb diets by subtracting fiber and sugar alcohols from total carbohydrates. Get instant, accurate results per serving.
Carb Calculator →Calculate your ideal daily carbohydrate intake in grams based on your TDEE and macro split goal, from low-carb to high-carb endurance diets.
Fiber Calculator →Calculate your recommended daily fiber intake in grams based on USDA age and sex guidelines, plus a calorie-based cross-check using the 14g per 1,000 kcal rule.

Related Terms

KetoKetogenic DietMacronutrientsProtein, Carbohydrates, and Fats

Frequently Asked Questions

Fiber isn't digested and absorbed by the body the way sugars and starches are, so it has minimal impact on blood sugar or ketone production even though it's technically a carbohydrate. Subtracting it gives a more accurate picture of the carbs that actually affect your metabolism.
Some low-carb food labels also subtract sugar alcohols (like erythritol or xylitol) alongside fiber, since many are only partially absorbed, though the exact impact varies by type. Check the specific sugar alcohol used if you're tracking closely, since some affect blood sugar more than others.
Subtract the fiber grams from the total carbohydrate grams listed on the label. The [Net Carbs Calculator](/net-carbs-calculator/) does this instantly if you enter both values.
Ketosis depends on keeping the carbs that actually affect blood sugar low, and since fiber doesn't meaningfully raise blood sugar, using total carbs instead of net carbs would cause someone to unnecessarily avoid high-fiber foods that don't actually threaten ketosis.
High-fiber vegetables (like broccoli, cauliflower, and leafy greens), nuts, seeds, and certain fruits like avocado and raspberries can have total carb counts that look high but net carb counts that are much lower once fiber is subtracted.