Net Carbohydrates
Digestible carbs after subtracting fibre and half of sugar alcohols.
Formula
Variables
Example
25 g − 8 g fibre ⇒ 17 g net
How it works
Net carbohydrates estimate the portion of total carbohydrates that is more likely to affect blood glucose. Fibre is subtracted because it is not digested the same way as starches and sugars, and sugar alcohols are only counted halfway here because many of them are only partially absorbed and produce a smaller glycaemic impact. This makes the formula a practical approximation rather than a perfect biological measure.
When to use it
Use this when comparing packaged foods, planning low-carb meals, or estimating how many carbs from a serving are likely to be "counted" by the body. It is especially useful on nutrition labels that list total carbohydrate, fibre, and sugar alcohols separately.
Worked example, step by step
A snack bar has 32 g total carbohydrates, 9 g fibre, and 6 g sugar alcohols. C_net = C_total - F - A/2 C_net = 32 - 9 - 6/2 C_net = 32 - 9 - 3 C_net = 20 g So the net carbohydrates are 20 g.
Common mistakes to avoid
- Subtracting all sugar alcohols instead of only half
- Using grams of sugar instead of total carbohydrates
- Forgetting that the formula is an estimate and label values may be rounded
Did You Know?
The "net carb" concept was popularised by low-carb and keto diets; regulators in some countries do not officially recognise it.
Share this formula
More in Nutrition & Food
View allFood Energy (Atwater)
BasicTotal food energy in kilocalories from its macronutrients using the Atwater factors.
Calories from Protein
BasicEnergy contributed by protein at 4 kcal per gram.
Calories from Carbohydrate
BasicEnergy from carbohydrate at 4 kcal per gram.
Calories from Fat
BasicEnergy from fat at 9 kcal per gram — the most energy-dense macronutrient.
Calories from Alcohol
IntermediateEnergy from pure alcohol (ethanol) at 7 kcal per gram.
Kilocalories to Kilojoules
BasicConvert dietary Calories to the SI energy unit used on many food labels.