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.
BMR is the calories you burn at complete rest. TDEE is your BMR plus all the calories from daily activity and exercise. TDEE is always higher and is the number you use to set weight-loss or weight-gain targets.
Mifflin-St Jeor is the most accurate for the general population. If you know your body fat percentage, Katch-McArdle is more precise because it's based on lean body mass rather than total weight.
No. Eating at only your BMR ignores the energy you spend moving, working, and exercising, so it usually creates too steep a deficit. Base your intake on your TDEE, then subtract a moderate deficit if you want to lose weight.