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BMR Calculator

Estimate your basal metabolic rate from sex, age, height, and weight, comparing the Mifflin-St Jeor and Harris-Benedict equations, with an optional daily calorie estimate.

Sex

Units

Calculated in your browser. Nothing is uploaded.

Enter your sex, age, height, and weight to see your BMR.

BMR is the energy your body uses at rest. These figures are estimates and vary with body composition, genetics, and health. They are not medical advice.

How to calculate your BMR

  1. Enter your details

    Select your sex, choose metric or imperial units, and type your age, height, and weight into the fields.

  2. Compare both estimates

    Your basal metabolic rate appears from both the Mifflin-St Jeor and Harris-Benedict formulas as soon as the fields are valid, with no button to press.

  3. Add an activity level

    Pick how active you are to see your estimated daily maintenance calories, then click Copy BMR summary to save the results.

Why use this tool

Two formulas, side by side

See your basal metabolic rate from both Mifflin-St Jeor and Harris-Benedict at once, with the newer Mifflin-St Jeor figure highlighted as the recommended estimate.

Metric and imperial input

Enter centimetres and kilograms, or switch to feet, inches, and pounds. Values are converted internally and the result updates as you type.

Daily calorie estimate

Choose an activity level from sedentary to very active to turn your BMR into a maintenance calorie target for the day.

Clear about its limits

Both formulas are estimates that use only sex, age, height, and weight, so the result comes with a plain note that real needs vary and it is not medical advice.

Your numbers stay on your device

Age, height, and weight are processed by the page alone. Nothing is uploaded, stored, or logged.

About this tool

This BMR calculator estimates your basal metabolic rate, the number of calories your body burns at complete rest to keep the essentials running: breathing, circulation, and cell repair. Enter your sex, age, height, and weight in metric or imperial and the result appears as you type, with no button to press. You get two figures side by side, one from the Mifflin-St Jeor equation and one from Harris-Benedict, so you can compare the two most widely used formulas at a glance.

The two equations use the same four inputs but different coefficients, so their answers usually sit within a few dozen calories of each other. Mifflin-St Jeor is the newer formula and is generally considered the more accurate one for most adults today, which is why it is highlighted here. Harris-Benedict, first published in 1919 and revised in 1984, tends to read a little higher. Neither is a medical measurement; real energy needs vary with body composition, genetics, and health, so treat both as a starting estimate. Set an activity level to turn your BMR into a rough maintenance calorie target for the day.

Your figures stay on your device: everything is worked out on the page and nothing you type is uploaded, stored, or logged. For related numbers, the BMI calculator relates your weight to your height, the age calculator turns a birth date into an exact age, and the unit converter handles standalone conversions such as pounds to kilograms.

Frequently asked questions

How is BMR calculated?
Basal metabolic rate is estimated from your sex, age, height, and weight. This tool uses two standard formulas, Mifflin-St Jeor and Harris-Benedict. Both combine the same four inputs with different coefficients, and the result updates as you type. Imperial entries are converted internally, so metric and imperial give the same answer.
Which formula is more accurate, Mifflin-St Jeor or Harris-Benedict?
For most adults today, Mifflin-St Jeor is generally considered the more accurate of the two, which is why it is highlighted as the recommended figure. Harris-Benedict is the older formula and usually estimates a slightly higher rate. Showing both lets you see the range rather than trusting a single number.
How do I turn BMR into daily calories?
Pick an activity level and the tool multiplies your Mifflin-St Jeor BMR by a standard factor, from 1.2 for sedentary up to 1.9 for very active. The result is your total daily energy expenditure, a rough estimate of the calories needed to maintain your current weight.
Can I use pounds, feet, and inches?
Yes. Switch the units toggle to Imperial to enter height in feet and inches and weight in pounds. Metric mode uses centimetres and kilograms. Either way the calculation is the same, because imperial values are converted to metric before the formulas run.
Is my data uploaded anywhere?
No. Everything runs in your browser; the age, height, and weight you enter are never uploaded, stored, or logged.
Is BMR the same as the calories I need to lose weight?
No. BMR is only the energy used at rest. Your full daily requirement is higher once activity is included, which is what the maintenance estimate shows. To lose or gain weight, people typically adjust intake around that maintenance figure, ideally with guidance from a health professional. These numbers are estimates, not medical advice.

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