Basal Metabolic Rate (BMR) Calculator

Estimate the calories your body burns at complete rest, compare three BMR formulas and turn the result into a daily calorie target.

Pick a starting point
Units
Sex
Advanced: choose a formula and activity level
Basal metabolic rate
0 kcal/day
Calories your body burns at complete rest to keep basic functions running.
How the three formulas compare
FormulaBMR (kcal/day)Best suited for
Mifflin-St Jeor-Most adults; modern general-purpose default.
Revised Harris-Benedict-Older equation; tends to read slightly higher.
Katch-McArdle-Lean or muscular people who know their body fat %.

From BMR to a daily calorie target

Lose weight (-15%)0 kcal/day
Maintain0 kcal/day
Gain weight (+10%)0 kcal/day

Total daily energy expenditure (TDEE) = BMR x activity factor. Cut, maintain and bulk targets adjust TDEE up or down.

BMR vs age for your parameters

The curve uses your current weight, height, sex and formula, varying only age. BMR naturally drifts down with age as lean mass changes.

For beginners: how to read this result
BMR is the floorIt is the energy used at rest, not what you should eat. You always burn more than this.
TDEE adds movementMultiplying BMR by an activity factor gives your real daily burn including activity.
Targets are rangesCut and bulk numbers are starting points; adjust after tracking your weight for a few weeks.
This is an estimate based on population formulas, not medical advice. Real metabolism varies with genetics, hormones, body composition and health. Consult a qualified professional before making big changes to diet or training.

To get a result, choose a starting preset or enter your own values: sex, age, weight and height. Use the unit toggle to switch between metric (kg, cm) and imperial (lb, ft/in). The advanced section lets you pick the formula and an activity level for the daily target.

The three formulas

The calculator shows your basal metabolic rate from three population equations so you can see how much they disagree.

  • Mifflin-St Jeor (default): BMR equals 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age in years, plus 5 for men or minus 161 for women.
  • Revised Harris-Benedict: a similar weight, height, age and sex equation that usually reads slightly higher.
  • Katch-McArdle: BMR equals 370 plus 21.6 times lean body mass in kilograms, where lean mass is weight minus the body fat percentage. The body fat field appears only when this formula is selected.

From BMR to a daily target

Basal metabolic rate is energy used at complete rest. Total daily energy expenditure (TDEE) is BMR multiplied by an activity factor from 1.2 (sedentary) to 1.9 (athlete). The bridge block converts TDEE into three targets: a cut at 85 percent of TDEE, maintenance at TDEE, and a bulk at 110 percent of TDEE.

What is not included

This estimate does not account for individual genetics, hormones, thyroid function, illness, medication, pregnancy, exact body composition or the thermic effect of specific foods. It is not a medical or nutrition prescription. The age curve varies only age and keeps your other inputs fixed, so it shows a trend rather than a personal forecast.