BMR Calculator
Calculate your Basal Metabolic Rate using both Mifflin-St Jeor and Harris-Benedict formulas. Know exactly how many calories you burn at rest.
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Mifflin-St Jeor (kcal/day)
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Harris-Benedict (kcal/day)
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Average BMR
Activity-based Calorie Needs (using Mifflin-St Jeor)
Frequently Asked Questions
What is BMR and why does it matter?
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions — breathing, circulation, cell production — while completely at rest. It represents the minimum energy your body requires just to stay alive.
What is the difference between Mifflin-St Jeor and Harris-Benedict?
Both estimate BMR from weight, height, age, and gender. The Mifflin-St Jeor equation (1990) is considered more accurate for most people. The original Harris-Benedict (1919) tends to overestimate BMR by about 5%, though a 1984 revision improved accuracy.
How does BMR relate to weight loss?
You should never eat below your BMR on a sustained basis. Doing so causes your body to break down muscle tissue for fuel, which actually slows metabolism. A safe calorie deficit is typically 500 kcal below your TDEE (BMR × activity factor), not below your BMR.
Does BMR decrease as you age?
Yes. BMR typically decreases by about 1–2% per decade after age 20, mainly due to loss of muscle mass. Regular strength training helps preserve muscle and maintain a healthier BMR as you age.
How can I increase my BMR naturally?
Build muscle through resistance training (muscle burns more calories at rest than fat), eat adequate protein to preserve muscle, avoid very low-calorie diets, stay hydrated, and get enough sleep. Regular exercise also temporarily raises metabolic rate.