BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at rest — using three proven scientific formulas. Know your baseline before planning any diet.
Three Formulas, Three Perspectives
Mifflin-St Jeor (1990) is currently considered the most accurate for most people. The American Dietetic Association recommends it. Harris-Benedict was originally published in 1919 and revised in 1984 — it tends to run slightly higher. Katch-McArdle uses lean body mass instead of total weight, making it more accurate for people who know their body fat percentage, especially athletes.
Why BMR Drops Over Time
BMR decreases roughly 1-2% per decade after age 20, primarily due to muscle loss (sarcopenia). This is why people often gain weight as they age even without changing their diet. Strength training helps counter this by maintaining lean mass. If you don't know your body fat percentage, our Body Fat Calculator can give you an estimate for the Katch-McArdle formula.
⚠️ Medical Disclaimer
This tool provides estimates for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making health decisions. Results may vary based on individual factors not captured by this calculator.