Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to keep you alive — breathing, circulation, cell repair. It's the baseline every diet or fitness plan builds on. This calculator uses the Mifflin-St Jeor equation, the most widely validated BMR formula, from your weight, height, age and sex.
Your BMR
1,618
kcal/day at complete rest
Informational estimate only — not medical advice. Consult a doctor or dietitian before making diet or fitness changes.
The Mifflin-St Jeor equation (1990), validated against indirect calorimetry:
It outperforms the older Harris-Benedict equation for most modern adults, but it's still an estimate — individual metabolism varies with muscle mass, genetics and health conditions.
A 30-year-old man weighing 70 kg at 175 cm:
The same woman: 700 + 1,093.75 − 150 − 161 = 1,483 kcal/day.
Your BMR is what you'd burn lying in bed all day — typically 60–70% of total daily expenditure. To maintain weight you need BMR plus activity calories (see the TDEE calculator); to lose weight you eat modestly below your total burn; to gain, modestly above.
Don't eat below your BMR for extended periods without medical supervision — that's the energy your organs need to function.
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Estimate your Total Daily Energy Expenditure from BMR and activity level. See how many calories you burn per day to plan diet, weight loss and fitness goals.
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Content last reviewed on 2026-10-06.