How many calories do you burn at rest?
Your Basal Metabolic Rate is the floor your daily calorie target is built on. Compare three clinical formulas and see daily totals at every activity level.
Your details
Your BMR
Mifflin-St Jeor (modern standard)
BMR is what you burn at complete rest — breathing, circulating blood, thinking. It's the floor your daily calories are built on.
Daily calories at each activity level
BMR × activity multiplier = estimated daily calorie needs (TDEE). Based on the Mifflin-St Jeor value.
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Three formulas, one number
BMR equations are all regressions from historical lab data — they differ in the populations studied and what inputs they rely on.
- Mifflin-St Jeor (1990): today's clinical gold standard for healthy adults.
- Harris-Benedict revised (1984):the original 1919 equation updated by Roza & Shizgal; slightly over-estimates on average.
- Katch-McArdle: uses lean body mass — most accurate when you have a reliable body-fat percentage.
From BMR to daily calories
BMR alone isn't your daily target — you also burn calories moving, training and digesting food. Multiply by an activity factor to get your Total Daily Energy Expenditure.
- Sedentary (desk job): BMR × 1.2
- Lightly active: BMR × 1.375
- Moderately active: BMR × 1.55
- Very active: BMR × 1.725
- Athlete: BMR × 1.9
Want the full TDEE readout with macro breakdown? Use the calorie calculator.
Frequently asked questions
What is BMR?+
Your Basal Metabolic Rate is the number of calories your body burns at complete rest in a thermally neutral environment — breathing, circulating blood, maintaining body temperature, and keeping your organs running. It accounts for roughly 60–75% of the calories you burn in a day.
What's the difference between BMR and TDEE?+
BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor (1.2–1.9) to include movement, exercise and the energy cost of digesting food. Your daily calorie target is based on TDEE, not BMR alone.
Which BMR formula is most accurate?+
For most adults, Mifflin-St Jeor (1990) is the most accurate of the equations that use only height, weight, age and sex — it's what dietitians use by default. Katch-McArdle is more accurate if you know your body fat percentage, because it works from lean mass rather than total weight.
Why does my BMR decrease with age?+
Two reasons: lean muscle mass tends to decline from the 30s onwards (sarcopenia), and organ metabolism slightly slows. Regular resistance training and adequate protein are the most effective countermeasures.
Can I eat below my BMR to lose weight faster?+
Not recommended. Eating below BMR for extended periods risks muscle loss, nutrient deficiency and metabolic adaptation. Create a calorie deficit below your TDEE (not your BMR) — typically 300–500 kcal/day — and pair it with protein and strength training.