BMR Calculator

1. Select your unit system. Imperial (lbs and inches) or Metric (kg and cm). Both use the same underlying formulas; the calculator converts units internally.
2. Enter gender, age, height, and weight. All four are required. BMR formulas were developed on population data, so results are averages. Your actual BMR may be 10-20% higher or lower based on individual metabolic variation and body composition.
3. Select your activity level. The calculator multiplies your BMR by an activity factor to produce your TDEE (Total Daily Energy Expenditure), which is your actual daily calorie burn including movement and exercise.
4. Compare the three BMR results. The Mifflin-St Jeor equation is the most accurate for most people. Harris-Benedict is the older standard, which tends to run slightly higher. Katch-McArdle is most accurate if you know your body fat percentage, as it uses lean body mass instead of total weight.

Three formulas are calculated, each developed through different research methods:

Mifflin-St Jeor (1990, most accurate for general population):
Male:   BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5
Female: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161

Harris-Benedict (revised 1984, older standard):
Male:   BMR = 88.362 + 13.397W + 4.799H - 5.677A
Female: BMR = 447.593 + 9.247W + 3.098H - 4.330A

Katch-McArdle (uses lean body mass):
BMR = 370 + 21.6 × lean body mass(kg)

Example: 28-year-old male, 5'10" (178cm), 185 lbs (84kg):

Mifflin-St Jeor: 10(84) + 6.25(178) - 5(28) + 5 = 1,897 cal/day
Harris-Benedict: 88.362 + 13.397(84) + 4.799(178) - 5.677(28) = 1,976 cal/day

Activity multipliers to convert BMR to TDEE: 1.2 (sedentary), 1.375 (lightly active), 1.55 (moderately active), 1.725 (very active), 1.9 (extra active).