Check the label format first
US and Canadian total carbohydrate figures include fiber. UK and EU carbohydrate figures exclude it. Select the appropriate format before entering values. Use the same basis for every input: one serving, 100g, or a whole package.
The calculation
Estimated net carbs = carbohydrate minus included fiber minus your chosen polyol deduction minus included allulose. The result is then divided by the portions covered by the figures and multiplied by the portions eaten.
For example, 20g total carbohydrate, 8g fiber and 6g erythritol gives 6g estimated net carbs when erythritol is deducted in full. Eating half that labeled portion gives 3g.
Sugar alcohols and allulose
Erythritol is commonly deducted in full for food tracking. The half-deduction option for other polyols is a tracking convention, rather than a measured absorption rate. Choose no deduction if you want to retain their full labeled carbohydrate amount.
Allulose is a sugar, rather than a sugar alcohol. Under FDA guidance, it remains in total carbohydrate even when excluded from the total and added sugars lines. Enter it separately, and only deduct it when it is included in the carbohydrate figure. If its quantity is unknown, leave the input at zero.
Serving sizes and rounded labels
If your figures cover four servings and you ate two, enter 4 for portions covered and 2 for portions eaten. Values printed as zero can be rounded, so multiplying a small labeled portion can accumulate unshown amounts. This tool cannot recover those amounts.
Compare ingredient portions in the food comparison tool, or read allulose vs erythritol for baking and label differences.
Frequently asked questions
How do you calculate net carbs from a US label?
Start with total carbohydrate, subtract included dietary fiber, and choose how much of the listed sugar alcohols to deduct. Allulose has a separate input. This is a food-tracking estimate.
Should I subtract fiber from a UK or EU label?
The carbohydrate line on UK and EU labels already excludes fiber. Select that label format to avoid subtracting fiber twice.
Can I calculate half a serving or a whole package?
Yes. Enter the number of portions covered by your label figures, then enter the portions you ate. Fractions such as 0.5 are allowed.
Does a net-carb result predict ketosis or blood glucose?
No. This calculator performs label arithmetic. It cannot determine how an individual responds to a food or set a therapeutic carbohydrate target.