What is basal metabolic rate?

BMR is the energy your body needs at complete rest to maintain vital functions. It represents 60–75% of total daily energy expenditure and is the starting point for calculating calorie targets.

Which BMR formula is most accurate?

Mifflin-St Jeor is considered most accurate for most adults and is recommended by the Academy of Nutrition and Dietetics. Katch-McArdle is more accurate for lean individuals with known body fat percentage.

Total Daily Energy Expenditure — BMR multiplied by an activity factor. This is the total calories burned per day and the number used to set weight management calorie targets.

How do I use BMR for weight loss?

Calculate your TDEE (BMR × activity factor), then subtract 500 kcal/day for approximately 0.5 kg/week weight loss. Never go below 1200 kcal (women) or 1500 kcal (men) without medical supervision.

Why does Katch-McArdle need body fat %?

Katch-McArdle calculates BMR from lean body mass (weight minus fat mass) rather than total weight. This makes it more accurate for muscular or lean individuals whose total weight overestimates metabolic need.

Is this BMR calculator free?

Yes — completely free, no sign-up required. Results export to CSV or print as PDF.

Medical › Nutrition & Metabolism

Basal Metabolic Rate (BMR) Calculator

Calculate your BMR using the three most validated clinical equations — Mifflin-St Jeor, Harris-Benedict (revised), and Katch-McArdle. See all three side by side, plus TDEE for every activity level and macronutrient targets.

⚡ Calculate Your BMR

Age (years)

Biological Sex

Weight (kg)

Height (cm)

Activity Level

Body Fat % (optional — for Katch-McArdle)

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BMR (Mifflin-St Jeor)

—

kcal/day at complete rest

All Three Equations

TDEE by Activity Level

Suggested Macros (for your TDEE)

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Basal Metabolic Rate — Formulas & Clinical Use

Basal Metabolic Rate (BMR) is the amount of energy your body requires at complete rest to maintain vital functions — breathing, circulation, temperature regulation, and cellular repair. It represents 60–75% of total daily energy expenditure and is the foundation for calculating calorie targets for weight management.

Mifflin-St Jeor (1990) — Recommended

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

Harris-Benedict Revised (1984)

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

Katch-McArdle (1975) — Best for lean individuals

BMR = 370 + (21.6 × lean body mass in kg)
Requires body fat percentage — use our body fat % calculator first.

Multiply BMR by an activity factor to get TDEE. For weight loss, subtract 500 kcal/day from TDEE. For muscle gain, add 250–300 kcal. See our calorie calculator for goal-based targets. Combine with ideal body weight and Fitness & Wellness tools.

⚠️ BMR equations are population-level estimates. Individual metabolism varies by ±15–20%. Adjust calorie targets based on real-world results over 2–4 weeks.