Why do we subtract fiber on Keto?

Fiber is a carbohydrate that the human body cannot digest. Since it doesn't break down into glucose, it doesn't raise blood sugar levels or trigger insulin, making it 'neutral' for ketosis.

Do all sugar alcohols count as zero?

Not all. Erythritol has a glycemic index of 0 and is usually fully subtracted. However, Maltitol has a glycemic index of 35 and can impact blood sugar, so many people only subtract half of the Maltitol grams.

Is there a limit to how much fiber I can subtract?

Technically no, but if a food label shows more fiber than total carbs, it's likely a regional label (like in the UK/EU) where fiber is already subtracted from the total carbs. Always check the label origin.

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Net Carb Calculator

Net Carb Calculator

On Keto, you only count the carbs that impact blood sugar. Find the "Net Carbs" of any food.

Result

Net Carbs

How This Net Carb Tool Works

The Net Carb Calculator is the essential filter for anybody following a Ketogenic or low-carb lifestyle. In the United States and Canada, food labels include fiber and sugar alcohols in the "Total Carbohydrate" count. This tool helps you isolate the Impact Carbs—the ones that actually affect your insulin levels.

Standard Calculation Logic

US/Canada Labels: Net Carbs = Total Carbs - Fiber - Sugar Alcohols.
UK/EU/Australia Labels: The 'Carbohydrate' line already excludes fiber. In these regions, you only subtract sugar alcohols (if present).

Example: Avocado vs. Low-Carb Tortilla

An Avocado has ~12g Total Carbs and 10g Fiber. Its Net Carb count is 2g, making it a Keto superfood.

Conversely, a 'Keto Tortilla' might have 15g Total Carbs and 12g Fiber. Even though its Net Carbs are 3g, some people find the modified corn starch used in these 'keto-friendly' products still impacts their ketosis. Always test your individual response.

Pro Tip: Beware of Maltitol. It is a common sugar alcohol in 'Sugar-Free' candies that still has a significant glycemic impact. If you see Maltitol, consider only subtracting 50% of those grams to stay safe.

Net Carb Intelligence FAQ

What about Allulose?

Allulose is a 'rare sugar' that is not metabolized by the body. Like Erythritol, you can subtract 100% of Allulose grams from your total carb count to find your net carbs.

Should I use Total Carbs instead?

Some 'Total Carb' purists argue that subtracting fiber allows for too many processed 'Keto' treats. If you are stalled in your weight loss, switching to a 20g-30g *Total* Carb limit is a common troubleshooting step.

Can fiber be negative?

No. If your math results in a negative number, you are likely looking at a non-US label where fiber is listed separately from carbohydrates. In that case, your Net Carbs are simply the Carbohydrate number shown.