BMR Calculator
Basal Metabolic Rate — the calories your body burns at rest. Uses the Mifflin-St Jeor equation, with Harris-Benedict and Katch-McArdle shown for comparison.
How to use
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Pick your sex — the formulas use different constants for men and women because of body composition differences.
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Enter age, height in cm, and weight in kg. The result updates instantly.
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Optionally enter body fat percentage. If you have a DEXA scan, BIA reading, or Navy-method estimate, the Katch-McArdle formula uses lean body mass and is more accurate than Mifflin or Harris-Benedict for very lean or very muscular bodies.
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The main result is the Mifflin-St Jeor BMR. That's the calories your body uses at complete rest — sleep, breathing, organ function.
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Multiply by an activity factor (shown in the result panel) to get your daily maintenance calories. The Calorie Calculator does this for you with a single click.
Frequently asked questions
BMR is Basal Metabolic Rate — the number of calories your body burns to stay alive at complete rest. It accounts for the energy to keep your heart beating, lungs breathing, brain functioning, body temperature stable, and cells repairing. For most adults it's 60-75% of daily total energy expenditure.
Mifflin-St Jeor (1990) is the most accurate predictive formula for the general adult population — a 2005 meta-review found it within ±10% of measured BMR for 82% of subjects. Harris-Benedict (1919) over-estimates by 5-8% on average. Katch-McArdle is the most accurate IF you have a reliable body-fat percentage measurement, because it uses lean body mass directly.
BMR is calories at rest. TDEE (Total Daily Energy Expenditure) is BMR plus all the calories you burn from activity — walking, exercise, fidgeting, even chewing. TDEE = BMR × activity factor. A sedentary office worker has TDEE ≈ BMR × 1.2; an athlete TDEE ≈ BMR × 1.9.
No. Eating exactly at BMR is dangerous long-term — your body needs energy for daily activity too. To lose weight safely, eat 300-500 kcal below your TDEE (not BMR), and combine with strength training to preserve muscle. Severe restriction (eating below BMR) slows metabolism and triggers muscle loss.
Two reasons. First, lean body mass (muscle) naturally declines about 3-5% per decade after age 30 — and muscle burns more calories than fat at rest. Second, organ activity slightly decreases. The result: BMR drops about 1-2% per decade. Resistance training in your 40s, 50s, 60s+ slows this dramatically.
Yes. At the same height, age, and weight, men typically have ~10% higher BMR than women due to higher lean body mass and lower body fat percentage. Mifflin-St Jeor and Harris-Benedict both use sex-specific constants. Katch-McArdle uses lean body mass directly so the formula is the same for both sexes.
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Source: Mifflin et al. (1990) Am J Clin Nutr; Frankenfield et al. (2005) J Am Diet Assoc · Last verified 2026-06. Verify on PubMed. This tool provides estimates only and is not legal, tax or financial advice. Always verify your specific situation with the relevant UAE authority or a licensed advisor before taking action.