FreeToolStation

BMR Calculator

The energy your body uses at complete rest.

Health Calculators Free, no sign-up Runs in your browser

The equations were derived separately for each.

Optional. Enables the Katch-McArdle equation, which uses lean mass instead of sex.

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BMR (Mifflin-St Jeor)
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Per hour
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Harris-Benedict
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Katch-McArdle
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Daily need if sedentary
Activity levelMultiplierDaily calories
BMR is energy used at complete rest: breathing, circulation, cell repair. It is not a target to eat, and the real figure varies between people of identical height, weight and age by several hundred calories.

About the BMR Calculator

BMR Calculator estimates basal metabolic rate: the energy your body uses doing nothing at all. Breathing, circulating blood, maintaining temperature and repairing cells account for the majority of most people's daily energy use, well before any activity is added.

Three equations are shown because they disagree, and seeing by how much is the honest way to present an estimate. Mifflin-St Jeor is the default: it was published in 1990 and validates better than the older Harris-Benedict for modern populations. Katch-McArdle uses lean body mass instead of sex and height, which makes it the most accurate of the three for anyone who knows their body fat percentage and is unusually lean or unusually muscular.

The activity table multiplies BMR up to a daily total, and the multipliers are rough by nature. The gap between sedentary and moderately active is around 500 calories a day for a typical adult, which is larger than the difference between any two of these equations -- so an honest assessment of activity matters more than which formula you pick.

This is general information and not medical advice. The formula cannot know your medical history, your medication, your body composition or anything else specific to you. Speak to a doctor or another qualified professional about any question concerning your health, and never delay seeking advice because of a figure on this page.

Your measurements are processed inside your own browser. Height, weight, age and anything else you enter never leave your device, nothing is logged, and nothing survives closing the tab.

Looking for something this does not cover? FreeToolsHub.org is another hub of free online tools that need no account, and it is worth a look if bmr calculator is only part of what you are working on.

How to use the BMR Calculator

  1. Choose sexThe fields below change to match what you pick, so only the figures that matter to your case are asked for.
  2. Enter age (years), weight (kg) and height (cm)Decimals are fine, and thousands separators are accepted and ignored.
  3. Read the bmr (mifflin-st jeor), per hour and harris-benedictThe figures update as you type. The Calculate button is there if you would rather press something, but nothing waits for it.
  4. Copy or check the resultCopy the summary with the copy button, or open the table to check it row by row.

Features

  • Shows bmr (mifflin-st jeor), per hour, harris-benedict, katch-mcardle and daily need if sedentary together, so you are not running it twice
  • A results table you can read across
  • Updates as you type, with no button to press and no page reload
  • Copy the result in one click
  • Free, no sign-up, and it runs entirely in your browser

Who uses this tool

The bmr calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

  • Finding a baseline before setting a calorie target
  • Comparing the common BMR equations on your own figures
  • Understanding how much energy rest alone accounts for
  • Estimating daily needs at different activity levels

Frequently asked questions

Which BMR equation is most accurate?

Mifflin-St Jeor for most people, and Katch-McArdle if you have a reliable body fat measurement. Harris-Benedict is older and tends to run high.

Is BMR the same as the calories I should eat?

No. BMR is rest only. Daily need is BMR times an activity multiplier, and the table shows that range.

Why do two people with the same stats differ?

Because body composition, thyroid function, genetics and medication all affect metabolic rate. An equation can only use what you type in.

If the bmr calculator is not quite what you need, these other free tools solve closely related problems, and there are 19 more in health calculators.

Calorie Calculator

Daily calorie needs from BMR and activity level.

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BMI Calculator

Work out BMI from height and weight, in metric or imperial units.

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Body Fat Calculator

Body fat percentage by the US Navy tape method.

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Macro Calculator

Split daily calories into protein, carbs and fat.

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Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.