Calculate your Basal Metabolic Rate — the calories your body burns at complete rest — using the Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas.
| Formula | BMR (cal/day) |
|---|---|
| Mifflin-St Jeor | — |
| Harris-Benedict | — |
| Katch-McArdle | — |
Your Basal Metabolic Rate (BMR) is the number of calories your body needs just to stay alive at complete rest — to power your heart, lungs, brain, and other organs. It typically accounts for 60–70% of the calories you burn each day. Knowing your BMR is the foundation for setting any calorie target.
The Mifflin-St Jeor equation is the modern standard and the most accurate for most people. Harris-Benedict is the classic formula, revised in 1984, and tends to read slightly higher. Katch-McArdle uses your lean body mass instead of total weight, so it's the most accurate option if you know your body fat percentage — especially for lean, muscular people.