BMR calculator

Your basal metabolic rate is what your body burns keeping you alive: heart, brain, lungs, temperature, doing nothing at all for 24 hours. It's the floor everything else is built on.

Milo

Sex

Age

Weight (kg)

Height (cm)

Body fat % (optional)

Your BMR will appear here.

How this is worked out

The default is Mifflin-St Jeor, which has held up better against measured data than the older Harris-Benedict equation:

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age {+5 male / −161 female}

Enter a body fat percentage and you also get the Katch-McArdle estimate, which works from lean mass instead: 370 + 21.6 × lean mass. When you genuinely know your composition, that’s usually the better number, because muscle and fat don’t burn the same at rest.

BMR falls with age and with weight loss, which is why a number you calculated two years ago is probably wrong now. It’s also not what you should eat: it’s the starting point for total daily burn, not a target.

The number is the easy part

Any calculator can hand you a figure. The hard bit is the next three months: eating roughly to it, noticing when it stops working, and changing it. Milo is a coach you text like a friend. You log what you ate in a sentence, and it learns your patterns, notices when your weight stalls, and adjusts the target from what you actually did rather than from a formula.

See how Milo works

Common questions

Should I eat at my BMR?

No. BMR is what you’d burn in a coma. Even a sedentary day is roughly 20% above it, and most people are 40-70% above once movement and training are counted. Eating at your BMR is an aggressive crash diet by accident.

What's the difference between BMR and TDEE?

BMR is at rest; TDEE is BMR plus everything you do. TDEE is the number you set a calorie target from, and it’s what the TDEE calculator gives you.

Why did my BMR drop after losing weight?

There’s less of you to keep running, so the arithmetic falls. There’s also a modest additional slowdown beyond what the size change predicts, which is why targets need revisiting every few kilos rather than being set once.

Mifflin or Katch-McArdle?

Katch-McArdle if you know your body fat from a scan or calipers, since it accounts for composition. Mifflin if your body fat figure is itself a guess, because feeding a guess into a more precise formula doesn’t make the answer more precise.

Other calculators

TDEE calculator — How many calories you burn in a day, and what to eat for your goal.
Calorie deficit calculator — How long a given deficit takes to reach your goal weight.
Protein calculator — Your daily protein target, based on lean mass rather than bodyweight.
Macro calculator — Calories split into protein, carbs and fat for your goal.
One rep max calculator — Your estimated 1RM from a working set, plus a full rep-max table.

These are estimates from population averages, not measurements of you. Individual metabolism varies by roughly ±10% around any formula. Nothing here is medical advice — if you have a health condition, are pregnant, or are under 18, talk to a healthcare professional before changing how you eat or train.