BMR Calculator

Basal metabolic rate (BMR) is the energy your body needs just to stay alive at rest: breathing, circulation and keeping warm. It is the starting point for working out how much to eat.

Sex
Height in
Weight in
Results update as you type.

BMR (Mifflin-St Jeor)

1,598 kcal a day

calories your body uses at complete rest

Harris-Benedict (revised)
1,645 kcal
With little or no exercise
1,917 kcal
With light exercise 1–3 days a week
2,197 kcal
With moderate exercise 3–5 days a week
2,476 kcal
With hard exercise 6–7 days a week
2,756 kcal
With very hard exercise or a physical job
3,035 kcal

About this calculator

Enter sex, age, height and weight. Mifflin-St Jeor is considered the most accurate everyday formula; the revised Harris-Benedict is shown for comparison.

How to use it

  1. Choose your sex and enter your age.
  2. Enter height and weight.
  3. Read your BMR and the calories at each activity level.

The formula

Mifflin-St Jeor: 10 × weight + 6.25 × height − 5 × age + 5 (men) or − 161 (women)
weight
kg
height
cm
age
years

Worked example

A 30-year-old man, 170 cm, 68 kg

  1. BMR = 10 × 68 + 6.25 × 170 − 5 × 30 + 5 = 1,598 kcal a day.
  2. Harris-Benedict gives 1,645 kcal.
  3. With moderate exercise, he burns about 2,476 kcal a day.

What the result means

You burn more than your BMR every day because you move and digest food. Use the TDEE calculator for your real daily need.

Assumptions

  • Healthy adult.

Limitations

  • Formulas are within about 10% for most people; muscle, illness and thyroid problems change real BMR.

Frequently asked questions

What is a normal BMR?

Roughly 1,200 to 1,500 kcal for women and 1,500 to 1,900 for men, depending on size and age.

Should I eat only my BMR?

No. Eating below BMR for long is not advised; your daily need is higher.

Does BMR fall with age?

Yes, by a few percent each decade, mainly from loss of muscle.

Not medical advice. This calculator is a general screening tool and cannot diagnose any condition. Results are estimates. Please talk to a doctor or a qualified health professional about your health and before making changes to diet, exercise or treatment.

Last reviewed on 1 October 2026. Found a mistake? Tell us.