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BMR Calculator

Estimate your basal metabolic rate — the calories your body uses at complete rest just to stay alive — from your age, sex, height and weight.

Quick answer

Mifflin-St Jeor: BMR = 10 × kg + 6.25 × cm − 5 × age + 5 for men (−161 for women). A 30-year-old man at 80 kg and 180 cm burns about 1,780 kcal a day at rest. Add daily activity with the TDEE calculator.

  • Free
  • No sign-up
  • Fitness
  • Updated October 2026

Used by the formulas; they were derived from male and female study groups.

years
lb
ft
in

BMR (Mifflin-St Jeor)

1,737 kcal/day

BMR (revised Harris-Benedict)
1,804 kcal/day
Per hour at rest
72 kcal
Show the working
  1. Mifflin-St Jeor = 10 × 77.1 + 6.25 × 177.8 − 5 × 30 + 5 = 1,737 kcal

About the BMR calculator

Your BMR covers breathing, circulation, temperature control and cell repair. For most people it is the largest part of daily energy use — often 60–70% — even before any movement or exercise.

The calculator uses the Mifflin-St Jeor equation, which studies have found to be the most accurate of the common formulas for most adults, and shows the revised Harris-Benedict result alongside. Both are population estimates; your real figure can differ by 10% or more.

How to use it

  1. Choose units and sex.
  2. Enter age, weight and height.
  3. Read your BMR. To include daily activity, use the TDEE calculator.

The formula

BMR = 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women)

  • This is the Mifflin-St Jeor equation (1990).
  • Revised Harris-Benedict (men): 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age.

Worked example

A 30-year-old man, 80 kg, 180 cm

  1. 10 × 80 = 800.
  2. 6.25 × 180 = 1,125.
  3. 5 × 30 = 150.
  4. 800 + 1,125 − 150 + 5 = 1,780 kcal a day.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is energy at complete rest. TDEE adds everything else — walking, work, exercise and digesting food — so it is always higher.

Should I eat my BMR in calories?

Eating at or below BMR is a very low intake for most people. Plan from your TDEE instead, and get medical advice before any very-low-calorie diet.

Does muscle raise BMR?

Yes, modestly. Lean tissue uses more energy than fat at rest, which is why the formulas use weight and why strength training helps maintain metabolism with age.

Results are estimates for healthy adults, not medical advice. Talk to a doctor or registered dietitian before major changes to diet or training, especially if you are pregnant or have a health condition.

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