Net carbs calculator

How to calculate net carbs

1. Enter the carbohydrates. Total carbohydrates in grams per 100 grams (from the packaging label).
2. Enter the dietary fibre. The amount of fibre in grams per 100 grams.
3. Add the sugar alcohols. If the product contains, for example, erythritol or xylitol.
4. Set the portion size. You also get the net carbs for the portion you choose.

What are net carbs?

Net carbs mean the carbohydrates that the body absorbs and that affect blood sugar. Dietary fibre is barely absorbed, so it is subtracted from the total carbohydrates. About half of the sugar alcohols is often subtracted, because they are only partly absorbed. A common way to calculate is: net carbs = carbohydrates − fibre − ½ × sugar alcohols. The concept is popular especially in low-carbohydrate and ketogenic diets.

Notes and limitations

Net carbs is not an official nutritional term everywhere, and EU packaging labels usually state carbohydrates and, of these, sugars, not fibre as part of carbohydrates in the same way as, for example, in the United States. Always check the nutritional content on the packaging and note that the effect of sugar alcohols varies by product and by individual. The calculator gives an estimate — it is not nutritional or health advice.

Example: a protein bar

The protein bar's packaging says per 100 grams: carbohydrates 40 g, of which dietary fibre 10 g and sugar alcohols 20 g. Net carbs are calculated by subtracting the fibre entirely and about half of the sugar alcohols: 40 − 10 − (20 / 2) = 40 − 10 − 10 = 20 g / 100 g. If the bar weighs 50 g, its net carbs are half of this, i.e. about 10 g. The calculator shows both the per-hundred-gram and the per-portion value.

Net carbs in different diets

Calculating net carbs is most common in low-carbohydrate and ketogenic diets, where the amount of absorbable carbohydrates is tracked closely. The idea is that fibre and some of the sugar alcohols do not raise blood sugar in the same way as other carbohydrates. However, not everyone reacts to sugar alcohols in the same way, and consuming a lot of them can cause stomach discomfort. The concept is not official everywhere, so use the figure as a rough guide and always check the packaging labels.

Glycaemic load and net carbs

Net carbs estimate the amount of absorbable carbohydrates, but they do not tell how quickly blood sugar rises. That is affected by the glycaemic index, which describes the speed of the rise in blood sugar caused by a food. The glycaemic load combines these: it takes into account both the quality of the carbohydrate and the amount of the portion. Two foods can contain the same amount of carbohydrate but affect blood sugar very differently.

In practice, net carbs and the glycaemic load complement each other. In a low-carbohydrate diet the net amount is often tracked, while those interested in the steadiness of blood sugar also look at quality. Neither figure alone is a perfect measure, and individual differences are large. This calculator gives an estimate of net carbs based on packaging labels; a complete picture of nutrition emerges when you also consider the quality of the food and your own body's reactions.

Good to know about net carbs

• Net carbs = carbohydrates − fibre − about half of the sugar alcohols.
• Fibre and some of the sugar alcohols barely raise blood sugar.
• The effect of sugar alcohols varies by individual and can cause stomach discomfort in large amounts.
• The concept is not official everywhere — always check the packaging labels.

In summary

The net carbs calculator computes the net carbs value by subtracting the fibre and half of the sugar alcohols. Enter the nutritional content per hundred grams, and you get the net carbs per portion as well, and you see the formula. The tool is aimed especially at a low-carbohydrate diet, but the figure is an estimate — always check the packaging labels.

Frequently asked questions