BMR Calculator
Estimate basal metabolic rate from height, weight, age and sex using published equations, with the formula named. An estimate, not medical advice.
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1,364 kcal per day at rest
Mifflin MD et al., Am J Clin Nutr 1990 — the equation most validated for adults
| Activity | Multiplier | kcal / day |
|---|---|---|
| Sedentary — Desk work, little or no exercise | × 1.2 | 1,637 |
| Lightly active — Light exercise 1–3 days a week | × 1.375 | 1,876 |
| Moderately active — Moderate exercise 3–5 days a week | × 1.55 | 2,114 |
| Very active — Hard exercise 6–7 days a week | × 1.725 | 2,353 |
| Extremely active — Physical job plus hard training | × 1.9 | 2,592 |
How this is calculated
About BMR Calculator
An estimate of the energy your body uses at complete rest, from height, weight, age and sex, using a published equation that is named on the page. It is the base figure other calorie targets are built on, and it is an estimate rather than a measurement. A free online calculator that keeps no records at all. Figures you type are worked through here and then discarded.
How to use BMR Calculator
- Enter your detailsHeight, weight, age and sex, in whichever units you prefer.
- Read the resting figureWhat the equation estimates your body uses doing nothing at all.
- Apply an activity factor for a daily figureBMR multiplied by an activity multiplier gives total daily expenditure, which is the number diet targets actually use.
Why these equations only approximate
They were derived by fitting a curve to measurements of populations, so they describe an average person with your height, weight, age and sex. Your actual resting rate depends on body composition, genetics, thyroid function, medication and temperature, none of which appear as inputs. Two people with identical inputs can genuinely differ by several hundred calories a day.
What it does not do
- An estimate from a population equation, not a measurement of you. Only indirect calorimetry measures it properly.
- Muscle mass is not an input, so the figure is least accurate for people who are very lean or very muscular.
- Not medical or dietary advice. If you are managing a health condition, pregnant, or already under professional care, that guidance takes precedence over any figure produced here.
BMR Calculator: questions people ask
- How accurate is this?
- Within roughly ten percent for most people, and further out at the extremes of body composition. Treat it as a starting point to adjust from over several weeks of real-world results rather than a target to obey.
- Is BMR the same as the calories I should eat?
- No. BMR is at complete rest. Daily expenditure is BMR multiplied by an activity factor, and an intake target is derived from that and from your goal.
- Which BMR formula should I use?
- Mifflin–St Jeor is the usual default for adults. Harris–Benedict (revised) is the older equation many sites still use, and Katch–McArdle is more accurate when you know your body-fat percentage, because it works from lean mass.
Questions about ToolsVerse itself — privacy, cost, what happens to your files — are answered in the frequently asked questions.
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