Health & Fitness

BMR Calculator

Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation

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Basal Metabolic Rate
Per Hour

About BMR

BMR represents the number of calories your body burns at rest to maintain basic life functions like breathing, circulation, and cell production. The Mifflin-St Jeor equation is considered the most accurate formula for estimating BMR.

How it works

Estimates Basal Metabolic Rate, the calories your body burns at complete rest to maintain vital functions. BMR accounts for 60-75% of total daily calorie needs for most adults.

Formula
BMR (men)   = 10·mass + 6.25·height − 5·age + 5
BMR (women) = 10·mass + 6.25·height − 5·age − 161   (Mifflin-St Jeor)
Variables
  • massbody weight in kg
  • heightstanding height in cm
  • ageage in years
Worked example
Inputs: 35-year-old man, 80 kg, 180 cm
  1. 10 × 80 = 800
  2. 6.25 × 180 = 1125
  3. 5 × 35 = 175
  4. 800 + 1125 − 175 + 5 = 1755
Result: BMR ≈ 1,755 kcal/day
Notes
  • Multiply BMR by an activity factor (1.2-1.9) to estimate TDEE.
  • Mifflin-St Jeor is more accurate for modern populations than the older Harris-Benedict formula.

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Frequently Asked Questions

Basal Metabolic Rate is the number of calories your body burns at complete rest just to keep basic functions running: breathing, circulation, cell production. It accounts for 60-75% of total daily calories for most people.

The modern standard. For men: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age + 5. For women: subtract 161 instead of adding 5. It is more accurate than the older Harris-Benedict formula.

Genetics, age (BMR drops ~2% per decade after age 20), muscle mass (muscle burns more at rest than fat), hormones (thyroid especially), and body temperature all influence BMR.

BMR Calculator | ExaCalc