Free BMR calculator using the Mifflin-St Jeor equation: get your basal metabolic rate and daily calorie needs from weight, height and age.
Your Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest to maintain vital functions like breathing, circulation, and cell production. It accounts for about 60-75% of your daily calorie burn. Knowing your BMR helps you create an effective nutrition plan for weight management.
BMR (basal metabolic rate) is measured under strict fasting and rest conditions, while RMR (resting metabolic rate) is measured under easier, everyday resting conditions and is usually slightly higher. In practice, both are used to estimate resting calorie needs.
Muscle is metabolically active tissue: each kilogram of muscle burns more calories at rest than fat. That is why strength training and muscle gain raise your BMR over time, while crash dieting can lower it.
Yes. BMR tends to decline with age, mainly due to loss of muscle mass and changes in body composition. Staying active and doing strength training helps slow this decline.
Yes. Your BMR is the baseline; your TDEE adds activity. Eating below TDEE — but not below BMR — creates a sustainable deficit that preserves muscle.
The Mifflin-St Jeor equation is widely recommended for the general population. Older formulas like Harris-Benedict tend to overestimate for some groups. No formula is exact; treat the result as an estimate.
As you weigh less, your body needs fewer calories at rest. Recalculate your BMR every few kilograms so your calorie targets stay accurate.