Net Carbs Calculator
Find net carbs from total carbs, fiber and sugar alcohols.
Results update as you type.
This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
Net carbs are the carbohydrates that actually affect your blood sugar, and this calculator finds them, which is central to keto and low-carb eating. You enter the total carbohydrates, the fiber, and any sugar alcohols, all in grams, and it returns the net carbs and how many grams were subtracted. The idea is that not all carbohydrates raise blood sugar equally. Fiber passes through largely undigested and does not turn into glucose, so it is subtracted in full. Sugar alcohols, sweeteners like erythritol and xylitol found in many low-carb products, are only partially absorbed, so a common convention subtracts half their grams, though some approaches subtract all of certain sugar alcohols like erythritol. This calculator uses the half convention as a middle-ground estimate. The resulting net-carb figure is what low-carb and ketogenic dieters track, because keeping net carbs low is what maintains ketosis and steadies blood sugar, rather than restricting total carbohydrate that includes non-impactful fiber. Net carbs is not an officially regulated term, so food labels may calculate it differently; when in doubt, checking total carbohydrate is the most conservative approach. The result is clamped at zero, since net carbs cannot be negative. Use this to plan meals within a carb budget and to compare packaged low-carb foods. Enter your total carbs, fiber, and sugar alcohols to find net carbs.
Net carbs = total carbs − fiber − (sugar alcohols / 2)
Net carbs subtract the carbohydrates that have little effect on blood sugar. Fiber is subtracted in full because it is not digested into glucose, and sugar alcohols are subtracted at half their amount, a common convention reflecting that they are only partially absorbed. The result cannot go below zero.
Source:Net carbohydrate convention (low-carb nutrition)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter total carbohydrates.
- 2
Adjust the options
Adjust dietary fiber and sugar alcohols if they apply — sensible defaults are already set.
- 3
Read your result
Net carbs updates instantly as you type — no button to press.
Frequently asked questions
What are net carbs?
Net carbs are the carbohydrates that meaningfully affect blood sugar, calculated by subtracting fiber and part of sugar alcohols from total carbohydrates. Because fiber and sugar alcohols are not fully digested into glucose, they have little blood-sugar impact. Net carbs are the figure most low-carb and ketogenic dieters track instead of total carbohydrate.
Why is fiber subtracted from carbs?
Fiber is a carbohydrate your body cannot digest into glucose, so it passes through largely intact and does not raise blood sugar the way other carbs do. Because it has minimal effect on blood glucose and insulin, it is subtracted in full when calculating net carbs, leaving only the carbohydrates that actually impact blood sugar.
How are sugar alcohols handled?
Sugar alcohols such as erythritol, xylitol, and maltitol are only partially absorbed, so their blood-sugar impact is reduced. A common convention subtracts half their grams when computing net carbs, which this calculator uses. Some approaches subtract all of certain sugar alcohols like erythritol, which has almost no impact, so conventions vary between sources.
Are net carbs an official measurement?
No. Net carbs is not a term regulated by food-labeling authorities, so manufacturers and diet programs may calculate it differently, some subtracting all sugar alcohols, others only part. Because of this inconsistency, if you need to be strict, relying on total carbohydrate is the most conservative choice, while net carbs is a useful practical guide for low-carb eating.
Who uses net carbs?
People following ketogenic or low-carb diets track net carbs because keeping them low is what maintains ketosis and controls blood sugar, while still allowing fiber-rich vegetables that contribute little digestible carbohydrate. It lets dieters focus on the carbs that matter metabolically rather than avoiding all carbohydrate, including beneficial fiber, indiscriminately.