BMR calculator
Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest, just to keep you alive. FitCalcs works it out with the Mifflin-St Jeor equation, the formula UK dietitians use, and offers the Cunningham equation if you know your body-fat percentage. BMR is the starting point for your full daily calorie burn: multiply it by an activity factor to get your TDEE. This is general information, not personalised dietary advice.
How this is worked out
Mifflin-St Jeor is the resting-metabolism equation UK dietitians and the British Dietetic Association use as standard:
BMR = (10 x weight kg) + (6.25 x height cm) − (5 x age) + s
s = +5 for men, −161 for women
Cunningham is preferred when you know your lean body mass, because it tracks muscle directly. It tends to read higher than Mifflin-St Jeor for lean, muscular people:
BMR = 500 + (22 x lean mass kg)
lean mass = weight x (1 − body-fat % / 100)
Informational only, not medical or dietary advice. BMR is calories burned fully at rest. 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