BMR Calculator
Adjust the inputs below. Results update as you type.
How it works
Mifflin-St Jeor (men): BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. Women: same minus 161. Multiply by an activity factor (1.2–1.9) to get TDEE. BMR represents minimum energy for organ function—actual needs are always higher. Illness, muscle mass, and thyroid function significantly affect real metabolic rate.
Input guidance
- Use measured values (recent weight, height, activity level) rather than guesses.
- Recalculate every few weeks as your routine and body metrics change.
- Pair screening metrics with context such as sleep, stress, and medical history.
The formula
The Mifflin-St Jeor equation: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 (men) or − 161 (women). It estimates calories burned at complete rest.
Worked example
A 30-year-old man, 80 kg and 180 cm: BMR = 800 + 1,125 − 150 + 5 = 1,780 calories per day at rest.
More examples to test
- Maintenance case: keep activity constant and observe expected baseline ranges.
- Adjustment case: change only one major variable to understand sensitivity.
How to interpret results
Use results for awareness and planning, then validate with qualified medical or nutrition professionals for individualized decisions.
When this can be inaccurate
Population formulas cannot account for all biological factors such as medical conditions, medication effects, body composition differences, and genetics.
Sources
- Mifflin et al. (1990) — A new predictive equation for resting energy expenditure
- NIH — Dietary Reference Intakes for Energy
Change history
- July 2026: Published BMR estimate path with formula-choice limitations.
Site-wide corrections also appear on the corrections log.
Track calories, macros, and fitness progress
General wellness resource.
Frequently asked questions
What is BMR?+
Basal metabolic rate — the energy your body uses at rest to keep basic functions like breathing, circulation, and temperature running.
BMR vs. TDEE?+
BMR is calories at complete rest; TDEE adds activity. TDEE = BMR × an activity factor and represents your real daily calorie needs.
What lowers BMR?+
Aging, muscle loss, and very low-calorie dieting can reduce BMR. More muscle mass raises it, since muscle burns more at rest than fat.
Can this calculator diagnose a condition?+
No. It is a screening and education tool only, not a clinical diagnosis.
When should I seek professional advice?+
Seek professional advice when results are extreme, persistent, or conflict with symptoms, goals, or prior medical guidance.
Guided next steps
Want the full workflow? Use this calculator inside a step-by-step guide.