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BMR Calculator

Find your Basal Metabolic Rate — the calories your body burns at rest — with three validated formulas side by side, plus your daily burn at every activity level.

Only needed for the lean-mass-based Katch-McArdle estimate
Your BMR
—kcal / day
Mifflin-St Jeor Most accurate for most adults
Mifflin-St Jeor
—
kcal / day
1990 — today's standard recommendation
Harris-Benedict
—
kcal / day
1919 (revised) — tends to run slightly high
Katch-McArdle
—
kcal / day
Enter body fat % to unlock

Your daily burn (TDEE) at each activity level

Activity levelMultiplierDaily calories

Want a full calorie & macro breakdown for your goal? Use the TDEE & Macro Calculator →

Turn your BMR into a daily plan

NutriBalance saves your calorie target and tracks every meal against it — via barcode scan or AI food photo. Streaks, XP, and weekly leagues keep you consistent. 14-day free trial, no card required.

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How it works

The maths behind your BMR

Basal Metabolic Rate (BMR) is the energy your body spends at complete rest — running your organs, repairing cells, and maintaining body temperature. It accounts for roughly 60–70% of the calories you burn each day. This tool runs the three most-cited BMR equations so you can compare them.

Mifflin-St Jeor (1990) — recommended

Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

Revised Harris-Benedict (1984)

Men: BMR = 13.397 × weight (kg) + 4.799 × height (cm) − 5.677 × age + 88.362
Women: BMR = 9.247 × weight (kg) + 3.098 × height (cm) − 4.330 × age + 447.593

Katch-McArdle (lean-mass based)

Both: BMR = 370 + 21.6 × lean body mass (kg)
where lean body mass = weight × (1 − body fat % ÷ 100). Best for lean or muscular people because it ignores fat mass, which is metabolically near-inactive.
FAQ

Frequently asked questions

BMR is the calories your body burns at complete rest just to stay alive — powering your heart, brain, lungs, and cell repair. It's the largest single component of your daily burn (60–70%) and the foundation every calorie target is built on. Know your BMR, multiply by activity to get TDEE, then adjust for your goal.
BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to include movement, exercise, and the energy used to digest food. You eat at your TDEE to maintain weight — never at your BMR. Get your full TDEE and goal targets with the TDEE & Macro Calculator.
For most adults, use the Mifflin-St Jeor result — a 2005 review in the Journal of the American Dietetic Association found it the most accurate predictor of resting energy expenditure. If you're lean or muscular and know your body fat percentage, Katch-McArdle is often closer because it's based on lean body mass rather than total weight.
As a rule, no. Sustained eating below your BMR can accelerate muscle loss, worsen metabolic adaptation, and disrupt hormones — all of which make weight loss harder, not easier. Build your deficit from TDEE and keep daily intake at or above your BMR. Use the Calorie Deficit Calculator to find a safe target.
Multiply your BMR by your activity level to get TDEE, set that (adjusted for your goal) as your daily calorie target in NutriBalance, then log meals via barcode scanner, AI food photo, or search. The app subtracts each meal automatically and shows your remaining calories and macros — the home-screen widget shows it without even opening the app.