BMR Calculator

Find the calories your body burns at complete rest — the foundation of every diet and fitness plan.

Your Details

Gender

Weight70 kg

Height170 cm

Age30 years

Your BMR (Mifflin-St Jeor)

1,618

calories burned per day at complete rest

Daily Calories by Activity Level

Sedentary
Little or no exercise, desk job
1,942 kcal
Lightly Active
Light exercise 1-3 days/week
2,225 kcal
Moderately Active
Moderate exercise 3-5 days/week
2,508 kcal
Very Active
Hard exercise 6-7 days/week
2,791 kcal
Extra Active
Very hard exercise & physical job
3,074 kcal

What is the BMR Calculator?

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform its most basic life-sustaining functions — breathing, circulation, cell production — while at complete rest. It typically accounts for 60-70% of your total daily calorie burn.

This calculator uses the Mifflin-St Jeor equation, considered the most accurate BMR formula by the American Dietetic Association. Knowing your BMR is the first step to setting a calorie target: multiply it by an activity factor to get your maintenance calories, then adjust for weight loss or gain.

BMR Calculator Formula & How It Works

Men: 10W + 6.25H − 5A + 5 | Women: 10W + 6.25H − 5A − 161

W = Weight in kg
H = Height in cm
A = Age in years

The Mifflin-St Jeor equation estimates resting energy expenditure from weight, height, age, and sex. Men get a +5 constant and women −161, reflecting average differences in lean body mass. The result is in calories per day at complete rest — your real-world needs are higher once activity is added.

Worked Examples

30-year-old man, 75 kg, 175 cm

BMR = 10×75 + 6.25×175 − 5×30 + 5 = 1,699 calories/day at rest.

28-year-old woman, 60 kg, 162 cm

BMR = 10×60 + 6.25×162 − 5×28 − 161 = 1,312 calories/day at rest.

Expert Tips

Never eat below your BMR for extended periods — it can slow your metabolism and cause muscle loss.
Strength training increases muscle mass, which raises your BMR over time.
Recalculate after every 5 kg of weight change — BMR shifts as your body does.

BMR Calculator FAQs

What is the difference between BMR and TDEE?

BMR is the energy you burn at complete rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor — it represents your real daily calorie burn including movement and exercise.

Why does BMR decrease with age?

Muscle mass naturally declines with age while fat proportion rises, and muscle burns more calories at rest than fat. BMR drops roughly 1-2% per decade after age 20.

Is the Mifflin-St Jeor equation accurate?

Studies show it predicts measured resting metabolic rate within 10% for most people, outperforming the older Harris-Benedict equation. Very muscular or very lean individuals may get better estimates from the Katch-McArdle formula, which uses body-fat percentage.

Should I eat exactly my BMR calories to lose weight?

No. Set your intake relative to your TDEE (maintenance), not your BMR. A safe weight-loss target is 250-500 calories below TDEE, which typically keeps you above BMR.