How to use it
- Enter your Daily calories and your Body weight in kilograms.
- Choose the Goal and the Style of eating, then the number of Meals a day.
- Read the Grams a day, then the Split by nutrient table, which gives the grams for each meal.
How the split is set
Each gram of protein and of carbohydrate gives 4 kilocalories, and each gram of fat gives 9. Protein is set by body weight: the recommended allowance of 0.8 grams per kilogram for a healthy adult, or the lower end of the International Society of Sports Nutrition's 1.4 to 2.0 grams per kilogram for building or keeping muscle, or of its 2.3 to 3.1 grams per kilogram for losing fat while keeping lean mass.
The style of eating then fixes one nutrient. The balanced style takes 30 % of calories as fat, the high-protein style 25 %, and the low-carb style 20 % as carbohydrate, which is below the 25 % cut-off that the National Lipid Association uses for a low-carbohydrate diet. The other nutrient takes the calories that are left.
These figures are for information and are not medical advice. The ranges describe healthy adults. If you have kidney or liver disease, diabetes, or are pregnant, a doctor or dietitian should set the split.
Protein kcal = grams of protein x 4
Fat kcal = calories x fat share (balanced 30 %, high protein 25 %)
Carb kcal = calories - protein kcal - fat kcal
Low carb = carbohydrate kcal 20 % of calories; fat kcal is what is leftThe ranges the page checks
The Institute of Medicine's Acceptable Macronutrient Distribution Ranges (2005) are 45 to 65 % of calories as carbohydrate, 10 to 35 % as protein and 20 to 35 % as fat. The page warns when a split falls outside them. A warning is not an error; it means the split is unusual and worth checking with a dietitian.
Worked example: 2,000 kcal, 70 kg, building muscle, balanced
Protein: 1.4 x 70 = 98 grams, which is 392 kcal, or 19.6 % of 2,000 kcal.
Fat: 30 % of 2,000 is 600 kcal, which is 67 grams. Carbohydrate is what is left: 2,000 - 392 - 600 = 1,008 kcal, which is 252 grams, or 50.4 %.
| Nutrient | Share | Grams a day | Grams a meal (3 meals) |
|---|---|---|---|
| Protein | 19.6 % | 98 g | 33 g |
| Fat | 30.0 % | 67 g | 22 g |
| Carbohydrate | 50.4 % | 252 g | 84 g |
Frequently asked questions
Why does protein depend on my goal and not on the style of eating?
The protein need is set by body weight and by training, so it is fixed by the goal. The style of eating only decides how the rest of the calories are shared between fat and carbohydrate.
What is a low-carb diet by this calculator?
The calculator sets carbohydrate at 20 % of calories. The National Lipid Association describes low-carbohydrate diets as those with less than 25 % of calories from carbohydrate, so 20 % falls within that description.
Why do I get a warning about fat or carbohydrate?
The warning means the split is outside the Acceptable Macronutrient Distribution Range set by the Institute of Medicine. It is a flag to check the plan, not a sign that the plan is wrong for you.
Can I use this for a child or during pregnancy?
Not without a doctor or dietitian. The protein figures and the ranges are for healthy adults, and needs in children and pregnancy are set differently.
Are the figures I enter stored?
No. The split is calculated in your browser and nothing you enter is sent to us.
Sources
- Jäger R et al. 2017, ISSN position stand: protein and exercise (doi 10.1186/s12970-017-0177-8)
- Dietary Reference Intake: AMDR and protein RDA, IOM 2005 (Wikipedia)
- Low-carbohydrate diet: definitions by the National Lipid Association (Wikipedia)
- Atwater system: 4 kcal per gram of protein and carbohydrate, 9 for fat (Wikipedia)
Figures and text last checked on Tuesday, November 10, 2026.