Macro calculator
A macro split divides your daily calories into protein, carbohydrate and fat. FitCalcs sets protein per kilogram of body weight first, because that is the macro the research is clearest on, fixes fat at just over a quarter of your calories, and lets carbohydrate fill the rest. Enter your daily calories (your TDEE) and your goal, and you get grams of each per day. This is general information, not personalised dietary advice.
How this is worked out
The order is protein (per kilogram of body weight), then fat (a share of calories), then carbohydrate (whatever is left):
protein g = weight x (1.6 cut / 1.4 maintain / 1.8 bulk)
fat kcal = 27.5% of calories ÷ 9
carb g = remaining calories ÷ 4
Energy values used are 4 kcal per gram for protein and carbohydrate and 9 kcal per gram for fat. The protein figures sit inside the 1.4 to 2.0 g/kg range that the International Society of Sports Nutrition links to muscle retention and growth.
Informational only, not dietary advice. Adjust to appetite and training. Editorially reviewed by FitCalcs.
Source for the protein range: International Society of Sports Nutrition position stand on protein and exercise, 2017.
Common questions
How do I split my calories into macros?
Set protein first, then fat, and let carbohydrate fill the rest. FitCalcs sets protein per kilogram of body weight, fixes fat at just over a quarter of your calories (27.5%), and gives the remaining calories to carbohydrate. Enter your daily calories and goal and you get grams of each per day. This is general information, not personalised dietary advice.
How much protein does the macro calculator set?
It sets protein per kilogram of body weight, 1.4 g per kilogram to maintain, 1.6 g per kilogram when cutting to protect muscle, and 1.8 g per kilogram when building. Those figures sit inside the 1.4 to 2.0 g per kilogram range the International Society of Sports Nutrition links to muscle retention and growth.
How many calories are in each macro?
Protein and carbohydrate both provide about 4 calories per gram, and fat provides about 9 calories per gram. That is why the calculator can convert your macro grams back into calories and check they add up to your daily target. Alcohol, for reference, provides about 7 calories per gram.
Why set protein per kilogram rather than as a flat percentage?
Because protein need scales with body size, not with your calorie total. Setting it as a percentage of calories can leave a dieting person short, since their calories are low but their muscle-protecting protein need is not. Fixing protein per kilogram of body weight first, then splitting the rest, is the approach the research supports.
Email me when this updates
No account, no spam. Just a short note when we update our page on your macro split or add a related tool. Unsubscribe any time by replying.
Editor, FitCalcs
Oliver Mackman is the named editor of FitCalcs and a director of Best Business Loans Ltd (Companies House 16833937), the company that operates the site. He is accountable for its editorial standards, sourcing and corrections, and requires every result to cite the underlying equation and the named UK source behind it, with health tools carrying the appropriate not-medical-advice caveats.
Last reviewed: 24 September 2026