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Free BMR Calculator Online

Estimate your basal metabolic rate (BMR), the calories your body burns at complete rest, using the Mifflin–St Jeor and revised Harris–Benedict equations.

years
cm
kg

BMR is what your body burns at complete rest. For a daily calorie target with a weight-loss or muscle-gain goal, use the calorie calculator.

Your BMR (Mifflin–St Jeor)

1,699 kcal/day

Estimated calories burned at complete rest.
Revised Harris–Benedict
1,763 kcal/day

Daily calories by activity level

Sedentary (little or no exercise) ×1.2
2,039 kcal
Light (exercise 1–3 days/week) ×1.375
2,336 kcal
Moderate (exercise 3–5 days/week) ×1.55
2,633 kcal
Active (exercise 6–7 days/week) ×1.725
2,930 kcal
Very active (hard daily training or physical job) ×1.9
3,228 kcal

These are estimates, not medical advice. Actual needs vary from person to person.

The equations

With weight in kilograms, height in centimeters and age in years, the Mifflin–St Jeor equation (1990) is:

Men:   BMR = 10·weight + 6.25·height − 5·age + 5
Women: BMR = 10·weight + 6.25·height − 5·age − 161

The Harris–Benedict equation, as revised by Roza and Shizgal in 1984, is shown for comparison:

Men:   BMR = 88.362 + 13.397·weight + 4.799·height − 5.677·age
Women: BMR = 447.593 + 9.247·weight + 3.098·height − 4.330·age

If you use pounds and feet, convert first: kilograms = pounds ÷ 2.2046 and centimeters = inches × 2.54.

Worked example

Here is the Mifflin–St Jeor calculation for a 35-year-old woman who is 165 cm tall and weighs 65 kg:

  1. Weight term: 10 × 65 = 650.
  2. Height term: 6.25 × 165 = 1,031.25.
  3. Age term: 5 × 35 = 175, which is subtracted.
  4. Add the sex constant: 650 + 1,031.25 − 175 − 161 = 1,345.25, so her BMR is about 1,345 kcal/day.
  5. Multiply by an activity factor for daily calories. At a moderate level: 1,345.25 × 1.55 ≈ 2,085 kcal/day.

The revised Harris–Benedict equation gives her about 1,408 kcal/day. The two equations rarely agree exactly, which is a reminder that both are estimates.

From BMR to daily calories

Your total daily energy expenditure (TDEE) is your BMR multiplied by an activity factor. The calculator's table uses the Mifflin–St Jeor result. For the woman above:

TDEE for a 35-year-old woman, 165 cm, 65 kg (BMR 1,345 kcal/day).
Activity levelFactorDaily calories
Sedentary (little or no exercise)1.21,614
Light (exercise 1–3 days/week)1.3751,850
Moderate (exercise 3–5 days/week)1.552,085
Active (exercise 6–7 days/week)1.7252,321
Very active (hard daily training or physical job)1.92,556

Pick the level that matches your typical week, not your best week. Most people with desk jobs who exercise a few times a week fit the light or moderate rows.

How age changes BMR

In the Mifflin–St Jeor equation, each extra year of age lowers BMR by 5 kcal, so each decade takes off 50 kcal at the same height and weight:

Mifflin–St Jeor BMR in kcal/day.
AgeMan, 178 cm, 80 kgWoman, 165 cm, 65 kg
251,7931,395
351,7431,345
451,6931,295
551,6431,245
651,5931,195

These are population-based estimates, not medical advice. Your actual metabolism can be higher or lower depending on body composition, health conditions and other factors.

Frequently asked questions

Which equation should I use?

Mifflin–St Jeor is widely regarded as the more accurate of the two for healthy adults today, which is why it is the main result. The Harris–Benedict figure is shown so you can compare.

What is the difference between BMR and TDEE?

BMR is the energy you burn at complete rest just to keep your body running. TDEE adds everything else you do in a day, from walking to exercise, so it is always higher than BMR.

Should I eat my BMR in calories to lose weight?

Not necessarily. Eating at or below your BMR is a large deficit for most people. A common approach is to start from your TDEE and reduce it moderately; the calorie calculator can suggest a target for your goal.

Does BMR go down with age?

In the Mifflin–St Jeor equation it does, by 5 kcal per year, or 50 kcal per decade, if your height and weight stay the same. Changes in muscle mass over time also affect your real metabolism, which the equation cannot see.

Why doesn't the calculator use body fat?

Both equations use only age, sex, height and weight. People with more muscle than average may burn more than the estimate, and people with more body fat may burn less.

Why is a man's BMR higher than a woman's at the same size?

The Mifflin–St Jeor equation adds 5 for men and subtracts 161 for women, a gap of 166 kcal per day at the same age, height and weight. Men carry more lean mass on average, and lean tissue burns more energy at rest than fat.

Results are estimates for informational purposes and are not financial, medical or professional advice. See our methodology and disclaimer.