BMR Calculator

Calculate your Basal Metabolic Rate (BMR) from age, gender, height, and weight using the Mifflin-St Jeor formula to find how many calories your body burns at rest. Free online tool.

Gender

How to Use

  1. Enter body information

    Input your gender, age, height (cm), and weight (kg).

  2. Select activity level

    Choose your typical activity level from sedentary to very active.

  3. View results

    See your BMR and Total Daily Energy Expenditure (TDEE) based on your activity level.

What Is Basal Metabolic Rate (BMR)?

Basal Metabolic Rate (BMR) is the minimum amount of energy your body needs to sustain life — maintaining body temperature, breathing, heartbeat, blood circulation and cell renewal. It's the number of calories you'd burn lying still and doing absolutely nothing, and it accounts for roughly 60–75% of your Total Daily Energy Expenditure (TDEE).

BMR varies with weight, height, age and sex. The more muscle and the larger your frame, the higher it is, while it declines with age. BMR matters for dieting because dropping your calorie intake below your BMR pushes your body into energy-saving mode and slows your metabolism.

Practical Uses

  • Setting a weight-loss goal: Subtract 300–500 kcal from your TDEE to create a safe deficit.
  • Building muscle: Track changes in BMR to check how well your diet and training are working.
  • Managing your health: Use it as a baseline for offsetting age-related metabolic decline through exercise.

Calculation Formulas

This calculator shows two formulas side by side.

Mifflin-St Jeor (1990, recommended by the ADA)

Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

e.g. a man, 70 kg, 170 cm, age 30 → 10×70 + 6.25×170 − 5×30 + 5 = 700 + 1062.5 − 150 + 5 = about 1,618 kcal

Harris-Benedict (1984 revision)

Men: BMR = 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age

Same case → 88.362 + 937.79 + 815.83 − 170.31 = about 1,672 kcal. The two results usually differ by 50–150 kcal.

Frequently Asked Questions

What is BMR (Basal Metabolic Rate)?
BMR (Basal Metabolic Rate) is the minimum energy (calories) your body needs to stay alive even when you're lying down doing nothing. It's the calories spent on basic biological functions like breathing, blood circulation and cell production, and it accounts for 60–75% of your total daily calorie expenditure.
What's the difference between the Mifflin-St Jeor and Harris-Benedict formulas?
Mifflin-St Jeor (1990) reflects modern body composition and is the formula recommended by the American Dietetic Association (ADA). Harris-Benedict (1919, revised 1984) is an older formula that tends to overestimate for people with obesity. For the average adult the two differ by 50–150 kcal; we recommend using Mifflin-St Jeor as your baseline and treating Harris-Benedict as a reference for comparison.
How can I raise my BMR?
Building muscle through strength training raises your BMR. One kilogram of muscle burns about 13 kcal a day, while a kilogram of fat burns only about 4.5 kcal. Increasing protein intake also raises the thermic effect of food (TEF), temporarily boosting your metabolism. Beware: extreme calorie restriction actually lowers your BMR.
How does BMR change as you age?
BMR declines with age, dropping by about 2–3% per decade, mainly due to muscle loss and hormonal changes. If you don't deliberately do strength training after your 30s, your metabolism keeps falling, so you may gain weight even while eating the same amount.
What's the difference between BMR and TDEE?
BMR is the minimum calories you burn at complete rest, while TDEE (Total Daily Energy Expenditure) is your actual total expenditure — BMR plus the calories burned by daily activity and exercise. Eating below your BMR while dieting is dangerous, so adjust calories based on your TDEE. TDEE is usually found by multiplying BMR by an activity factor (sedentary 1.2 to very active 1.9).
Which formula's result should I trust?
For a normal-weight adult, using Mifflin-St Jeor — recommended by the American Dietetic Association — as your baseline is the most accurate. However, no formula directly accounts for body-fat percentage or muscle mass, so a ±10% margin of error is possible. Use both formulas together to gauge an approximate range.
Why do men and women have different BMRs at the same height and weight?
Women on average have a higher body-fat percentage and less muscle, so at the same weight and height their BMR is 100–200 kcal lower than men's. Both formulas apply different constants and coefficients by sex precisely to reflect these body-composition differences.
Can I plan my diet using the BMR result alone?
BMR is your minimum survival calorie level, so you should never eat below it. Base your actual diet on your TDEE rather than your BMR, adding or subtracting 300–500 kcal to match your goal. Crash dieting below your BMR causes muscle loss and rebound weight gain.
Updated 2026 — WHO standards

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