BMR Calculator (Basal Metabolic Rate)
This BMR calculator estimates how many calories your body burns at complete rest to keep you alive: breathing, circulation and cell repair. Enter your age, sex, height and weight to get your basal metabolic rate using the Mifflin-St Jeor equation, with other formulas to compare.
Your BMR is the energy used at rest to power vital organs. Your total daily calories (TDEE) add movement, exercise and digesting food, and are usually 20 to 90% higher. Plan your eating around TDEE, and treat BMR as the level you shouldn't regularly eat below.
Basal Metabolic Rate (BMR)
Mifflin-St JeorYour BMR is the energy your body burns every day at complete rest to keep organs functioning. Never eat below this level without medical supervision.
Hourly Burn
74 kcal
At complete rest
Harris-Benedict
1850 kcal
Comparison
Formula Comparison
| Method | Description | BMR |
|---|---|---|
| Mifflin-St Jeor | Standard recommendation (most accurate for general population) | 1780 kcal/day |
| Revised Harris-Benedict | Classic clinical standard (Roza & Shizgal 1984) | 1850 kcal/day |
Mifflin-St Jeor is the most validated formula for general adults. Katch-McArdle is preferred when body fat % is known.
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Clinical Equations
WHO, CDC, ACSM & Mifflin-St Jeor
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How to use BMR Calculator
- 1Select your biological sex and enter your age.
- 2Enter your height and weight in metric (kg, cm) or imperial (lb, ft/in).
- 3Optionally enter your body fat percentage to calculate the Katch-McArdle formula.
- 4Review your daily basal metabolic rate and formula comparison table.
BMR vs TDEE
Basal Metabolic Rate accounts for 60% to 75% of your daily energy expenditure. It represents the calories needed to keep your lungs breathing, heart beating, and organs functioning in a thermoneutral environment at complete rest.
Total Daily Energy Expenditure (TDEE) takes your BMR and layers on physical activity, daily non-exercise movement (NEAT), and the thermic effect of food (TEF).
Formulas compared
Mifflin-St Jeor is regarded by the Academy of Nutrition and Dietetics as the most reliable standard for adults. Harris-Benedict (revised 1984) remains a respected historical clinical benchmark. Katch-McArdle calculates expenditure directly from lean mass (FFM), making it exceptionally accurate for athletic individuals with known body fat percentage.
Frequently Asked Questions
Which BMR formula is most accurate?
Mifflin-St Jeor is the most accurate for most people in research comparisons. If you know your body fat %, Katch-McArdle can be more accurate for lean, muscular people.
What is a normal BMR?
Many adult women fall around 1,200 to 1,500 kcal/day and many men around 1,500 to 1,900 kcal/day, depending on body size, age, and lean muscle mass.
Can I increase my BMR?
Building lean muscle through progressive resistance training raises BMR modestly, as muscle tissue is more metabolically active than fat. Severe long-term calorie deficits can suppress BMR.
Should I eat my BMR to lose weight?
Eating at BMR is usually a larger deficit than needed. Use the TDEE or calorie deficit calculator to find a moderate, sustainable daily target.
Related Calculators
TDEE Calculator
Estimate your Total Daily Energy Expenditure and discover your true maintenance calories.
Calorie Calculator
Calculate your daily calorie needs for weight loss, maintenance, or muscle gain.
Calorie Deficit Calculator
Calculate a safe, sustainable calorie deficit to reach your goal weight on schedule.
Macro Calculator
Calculate your daily macronutrients (protein, carbs, and fat) for weight loss or muscle building.
BMI Calculator
Calculate your Body Mass Index in metric or imperial, with CDC youth LMS percentiles and Asian cut-offs.
Scientific Sources & Evidence
- World Health Organization (WHO) — Body Mass Index Classification
- CDC Growth Charts — BMI-for-age LMS Percentiles
- Mifflin et al. (1990) — Basal Metabolic Rate Predictive Equations
- NICE Guideline NG246 — Identification and Management of Overweight and Obesity
- American College of Sports Medicine (ACSM) — Exercise Testing & Prescription
- European Food Safety Authority (EFSA) — Dietary Reference Values for Water