Converts a single macronutrient’s grams directly to calories using the standard Atwater factors nutrition labels are built on.
How it works
The entered grams are multiplied by the selected macronutrient’s calorie-per-gram factor (4 for protein and carbohydrates, 9 for fat, 7 for alcohol).
What this does not include
This does not include summing multiple macronutrients from a full meal — for that, use this site’s meal calorie calculator instead. This tool converts one macronutrient at a time.
How to use this calculator
- Select the macronutrient and enter the grams.
Frequently asked questions
Why does fat have a higher calorie-per-gram factor?
Fat is a more energy-dense macronutrient — at 9 calories per gram, it holds more than twice the energy of protein or carbohydrates at 4 calories per gram each.
Are these the exact figures found on a nutrition label?
They’re the standard general factors nutrition labels are built on, the same figures used by the USDA’s FoodData Central database.
Is this the same as the site’s meal calorie calculator?
Same underlying Atwater factors, but this tool converts just one macronutrient at a time rather than summing all four from a full meal.
