Nutrition

BMR Calculator

Work out your basal metabolic rate, the calories your body burns at rest, and what it means for your daily calories.

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Fill in your details above to see your BMR and daily calorie needs

What is BMR?

Your basal metabolic rate (BMR) is the number of calories your body burns just keeping you alive: breathing, pumping blood, keeping you warm and running your organs. It is what you would burn lying in bed all day. For most people BMR makes up 60% to 70% of everything they burn, which is why it is the starting point for every calorie target.

The formulas

The calculator shows two estimates.

  • Mifflin-St Jeor (the headline number): 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, or −161 for women. Published in 1990, it is the equation most dietitians use today because it matches measured BMR more closely than older formulas.
  • Revised Harris-Benedict: the 1984 update of the original 1919 equation. It usually lands within 50 to 100 calories of Mifflin-St Jeor and is still common in older apps and textbooks.

If you know your body fat percentage, equations like Katch-McArdle can be more accurate for very lean or very muscular people, because muscle burns more than fat at rest.

BMR vs TDEE

BMR is your burn at rest. TDEE (total daily energy expenditure) adds everything else: walking around, working, exercising and digesting food. The table under your result multiplies your BMR by standard activity factors, from 1.2 for sedentary to 1.9 for very active, to estimate your TDEE. That TDEE, not your BMR, is the number to base a diet on. Eating at or below your BMR for long periods is rarely a good idea.

What changes your BMR?

  • Size. Bigger bodies burn more, so BMR falls as you lose weight.
  • Muscle. Muscle tissue burns more calories than fat at rest, one reason strength training helps long term.
  • Age. BMR drops by roughly 50 calories a day per decade, largely from losing muscle.
  • Sex. Men tend to have a higher BMR at the same weight because they carry more muscle on average.

Once you know your BMR, the next step is a daily target. Use the daily calorie calculator or the calorie deficit calculator if you want to lose weight, then track against it. Bento Bunny makes that part quick by logging meals from a photo or a sentence.

Frequently Asked Questions

What is a normal BMR?
Most adult women have a BMR between about 1,200 and 1,500 calories a day, and most adult men between about 1,500 and 1,900. Taller, heavier and more muscular people sit higher, and BMR falls slowly with age.
Is BMR the same as the calories I should eat?
No. BMR is what you burn at complete rest. Your daily needs (TDEE) are higher because you also move, work and exercise. To lose weight, eat a little below your TDEE, not below your BMR.
Which BMR formula is most accurate?
For most healthy adults, Mifflin-St Jeor is the most accurate of the common equations, which is why it is the headline number here. If you know your body fat percentage, Katch-McArdle can be better for very lean or very muscular people.
How can I increase my BMR?
Building muscle through strength training is the main lever, since muscle burns more at rest than fat. Eating enough protein and avoiding very aggressive diets also helps protect it. Most other claims, like special foods that boost metabolism, have tiny effects.
Does BMR go down when you lose weight?
Yes. A smaller body needs less energy, so BMR drops as you lose weight. That is one reason weight loss slows over time, and why it helps to recalculate your targets every 10 lb or so.

Related Tools

Daily Calorie Calculator

Turn your BMR into targets to lose, maintain or gain.

Calorie Deficit Calculator

Set a safe deficit and see your goal date.

Macro & Calorie Calculator

Get personalised daily macro targets.

Done calculating? Start tracking.

Bento Bunny uses AI to track your meals from a photo — calories, macros, and more. No manual logging required.

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