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BMR Calculator – Basal Metabolic Rate & Daily Calorie Needs

Your Basal Metabolic Rate (BMR) is the number of calories your body burns maintaining basic life functions at complete rest — heartbeat, breathing, temperature regulation, and cell repair. It's the minimum caloric floor below which sustained restriction causes muscle loss and metabolic adaptation, and it forms the starting point for every evidence-based calorie target.

This BMR calculator uses the Mifflin-St Jeor equation, validated as the most accurate widely available formula for estimating BMR in the general adult population. It also multiplies by activity factors to estimate your Total Daily Energy Expenditure (TDEE).

How to use the Bmr Calculator

Enter your age, sex, height, and weight.

View your BMR (calories burned at absolute rest).

Select your activity level to calculate your TDEE.

Use TDEE as the baseline for any calorie goal.

BMR Estimates by Demographics (Mifflin-St Jeor)
Profile	Approx. BMR	Sedentary TDEE	Moderately Active TDEE
Woman, 25, 5'4", 130 lbs	~1,350 kcal	~1,620 kcal	~2,093 kcal
Woman, 35, 5'6", 155 lbs	~1,475 kcal	~1,770 kcal	~2,286 kcal
Man, 25, 5'10", 165 lbs	~1,835 kcal	~2,202 kcal	~2,844 kcal
Man, 35, 6'0", 185 lbs	~1,940 kcal	~2,328 kcal	~3,007 kcal
Man, 55, 5'11", 190 lbs	~1,810 kcal	~2,172 kcal	~2,806 kcal

Bmr Calculator FAQ

What is the difference between BMR and TDEE?

BMR is calories burned at complete rest. TDEE (Total Daily Energy Expenditure) adds physical activity and the thermic effect of food. TDEE is the calorie level that maintains your current weight.

Why does BMR decrease with age?

Primarily because lean muscle mass decreases with age (sarcopenia). Muscle is metabolically more active than fat tissue, so less muscle means lower BMR. Resistance training counteracts this decline.

Is the Mifflin-St Jeor equation the most accurate?

Research consistently shows it predicts measured BMR within ±10% for most adults, outperforming the older Harris-Benedict equation. The Katch-McArdle formula can be more accurate for lean individuals if body fat percentage is known.

How do I use my BMR to lose weight?

Calculate TDEE (BMR × activity multiplier). Subtract 500 kcal/day for roughly 1 lb/week of fat loss. Don't drop below your BMR for sustained periods — this causes muscle loss and metabolic slowing.