BMR Calculator
Your basal metabolic rate (BMR) is the energy your body uses at complete rest just to stay alive — to breathe, circulate blood, and keep your organs running. This BMR calculator uses the Mifflin-St Jeor equation, the formula most dietitians and researchers consider the most accurate for healthy adults, taking your sex, weight, height, and age. BMR is the foundation for a calorie plan: it is the floor, and your total daily burn (TDEE) is BMR multiplied by an activity factor.
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Default result: 1,779
BMR Calculator · Result
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Basal metabolic rate
male × 176 lb × 70.9 in × 30
This calculator provides general estimates for educational purposes only and is not medical advice. Results are based on population formulas and may not reflect your individual circumstances. Consult a qualified healthcare professional before making changes to your diet, exercise, or health routine.
Reviewed by the calculators.dev team · Last updated 2026-06-23
Formula reviewed against Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51(2):241-7
How to calculate
Choose your sex, then enter your weight, height, and age. The calculator applies the Mifflin-St Jeor equation: 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then +5 for men or −161 for women. For a 30-year-old, 80 kg, 180 cm man that is 800 + 1125 − 150 + 5 = 1780 kcal/day. To turn BMR into the calories you actually burn in a day, multiply it by an activity factor — the TDEE calculator does that step for you.
Mifflin-St Jeor: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) + s, where s = +5 for men and −161 for women. Variables: weight in kilograms, height in centimetres, age in years. The result is kilocalories per day at rest. The equation was derived from a population study and is an estimate for a typical healthy adult, not a measured rate.
Example calculation
A 30-year-old man weighing 80 kg at 1.80 m has a Mifflin-St Jeor BMR of (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1125 − 150 + 5 = 1780 kcal/day burned at complete rest.
- bmr
- 1,780 kcal/day
Assumptions
- The Mifflin-St Jeor equation is fitted to healthy adults; it can be less accurate at the extremes of body size or for people with unusual body composition.
- BMR is calories at complete rest — it does not include any movement, digestion, or exercise (that is what the activity factor in TDEE adds).
- The sex constant (+5 male, −161 female) and the coefficients are population averages, so two people with the same inputs share the same estimate.
Common mistakes
- Treating BMR as your daily calorie target. BMR is the resting floor; eating only your BMR ignores everything you burn moving around — use TDEE for a daily goal.
- Entering height in metres instead of centimetres, which collapses the 6.25 × height term and produces a far-too-low BMR.
- Confusing BMR with RMR. Resting metabolic rate is measured slightly differently and runs a little higher, but the two are often used interchangeably.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the calories you burn at complete rest. TDEE is your total daily burn — BMR multiplied by an activity factor that accounts for movement and exercise. TDEE is always higher than BMR.
Why does the formula use a different number for men and women?
The Mifflin-St Jeor equation adds +5 for men and subtracts 161 for women to reflect average differences in body composition. Men typically carry more lean mass, which burns more energy at rest.
Is Mifflin-St Jeor the most accurate BMR equation?
For healthy adults it is generally the most accurate of the common prediction equations, outperforming the older Harris-Benedict formula. It is still an estimate — only indirect calorimetry measures BMR directly.
Should I eat as few calories as my BMR?
No. Your BMR is the bare minimum your body uses at rest. A sustainable plan is based on your TDEE with a moderate deficit, not on your BMR alone. Consult a professional before cutting calories sharply.