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 about 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
FitCalcs sets protein per kilogram of body weight first, because it is the macro the research is clearest on, then fixes fat as a share of calories, and lets carbohydrate fill the remainder.
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, with each figure citing its source.
Calculators and Data Desk, FitCalcs
FitCalcs' editorial desk builds and documents the calculators, citing the underlying equation and the UK dataset behind every number. Health-related tools are editorially reviewed, with figures cited to named UK sources.
Last reviewed: 12 June 2026