Calculate your Basal Metabolic Rate — the calories your body burns at complete rest. Compare 3 scientific formulas and understand exactly what your BMR means for your goals.
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If unknown, Katch-McArdle will be estimated
BMR Results — 3 Formulas Compared
💡 Recommended: Mifflin-St Jeor is the most validated formula for most adults. Katch-McArdle is most accurate if you know your body fat %.
What Your BMR Means
Calorie Needs by Activity Level
Multiply your BMR by an activity factor (TDEE) to find your total daily calorie needs:
What Is BMR?
Also searched as: bmr calculator free | basal metabolic rate calculator | how many calories do i burn at rest | bmr calorie calculator Optimized for US users with American units and terminology.
Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions — breathing, circulation, cell production, and temperature regulation — while at complete rest. It represents the minimum energy your body needs to survive if you did absolutely nothing all day.
BMR accounts for 60–75% of your total daily energy expenditure. This is why dramatic calorie restriction below your BMR is counterproductive — your body will downregulate metabolism to match the lower intake, making long-term fat loss harder.
Mifflin-St Jeor vs Harris-Benedict vs Katch-McArdle
The Mifflin-St Jeor equation (1990) is considered the most accurate for most adults and is recommended by the Academy of Nutrition and Dietetics. The Harris-Benedict equation (revised 1984) is older and tends to slightly overestimate BMR. The Katch-McArdle formula is unique — it uses lean body mass instead of total weight, making it the most accurate for people who know their body fat percentage, especially athletic individuals.
Use the BMR Calculator above — enter your values and get instant results. This free online tool calculates how to calculate bmr without any download or signup required. Results update in real time as you type.
Use the BMR Calculator above — enter your values and get instant results. This free online tool calculates bmr vs tdee without any download or signup required. Results update in real time as you type.
No. Consistently eating below your BMR can cause muscle loss, metabolic adaptation, nutrient deficiencies, and hormonal disruption. For fat loss, create a moderate deficit from your TDEE (total daily energy expenditure) — typically 300–500 calories below TDEE. This allows sustainable fat loss while preserving muscle mass.
Men generally have higher BMR because they have greater muscle mass and less body fat than women of the same weight. Muscle tissue is metabolically more active than fat tissue — it burns more calories at rest. Hormonal differences also play a role, particularly testosterone levels which support muscle maintenance.
Yes. BMR decreases roughly 1–2% per decade after age 30, primarily because of natural muscle mass loss (sarcopenia). Resistance training is the most effective way to slow this decline — preserving or building muscle keeps your metabolic rate higher as you age.