BMR Calculator
Estimate your Basal Metabolic Rate and daily calorie needs by activity level.
Your Basal Metabolic Rate is the number of calories your body burns just to keep you alive at complete rest — breathing, circulating blood, maintaining body temperature. It's the foundation for any calorie planning.
The Mifflin-St Jeor formula
This calculator uses the Mifflin-St Jeor equation, widely regarded as one of the more accurate BMR formulas for the general population: for men, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; for women, subtract 161 instead of adding 5. It replaced the older Harris-Benedict equation in most clinical and fitness contexts.
BMR vs. TDEE
BMR alone assumes zero activity — it's not what you should eat, it's your body's baseline. Multiply BMR by an activity factor to get TDEE (Total Daily Energy Expenditure), which reflects your actual calorie needs including movement, exercise, and daily activity. This calculator shows both.
Frequently asked questions
Does muscle mass affect BMR?
Yes — muscle tissue burns more calories at rest than fat tissue, so two people with the same weight but different body composition can have meaningfully different BMRs. This formula doesn't account for body composition directly, only height, weight, age, and sex.
Why does BMR decrease with age?
Metabolic rate naturally slows with age, partly due to gradual muscle loss and hormonal changes — this is factored into the formula, which is why the same height and weight produces a lower BMR at 50 than at 25.