BMR & Daily Energy Calculator
Estimate resting metabolic rate and total daily energy expenditure using the Mifflin-St Jeor equation.
Formula
Mifflin-St Jeor: BMR = 10w + 6.25h − 5a + s, then × activity factor
Tips
- This is an estimate from a population equation. Individual metabolic rates vary by roughly 10% in either direction even between people with identical measurements, which is why a range is shown alongside the figure.
- Activity multipliers are the least reliable part. Most people overestimate their activity level — if in doubt, choose the category below the one you were about to pick.
- The equation was derived from adults without medical conditions. Pregnancy, thyroid disorders, some medications and a history of significant weight change all shift the result, sometimes substantially.
- Sustained intake below roughly 1,500 kcal for men or 1,200 for women makes nutritional adequacy difficult and is normally something to do under medical supervision rather than alone.
- If food, weight or eating feels distressing or preoccupying, a number from a calculator is unlikely to help. Speaking to a GP or a registered dietitian is a better next step.
Frequently asked questions
Should I eat this many calories?
This tool estimates what your body uses; it does not tell you what to eat. Appropriate intake depends on your health, goals, medical history and a great deal this calculator has no knowledge of. A registered dietitian can advise on that properly, and will account for things a formula cannot.
Why does my figure differ from another calculator?
Different equations. Mifflin-St Jeor is used here because it is the most accurate for the general adult population, but Harris-Benedict, Katch-McArdle and others exist and give different results. None is exact for an individual.
Is a lower number better?
No. A lower basal rate simply means a smaller or older body, not a worse one. It is a description, not a score.