TDEE Calculator

Mifflin-St Jeor (the default) uses weight, height, age, and sex, and a systematic review found it predicts resting metabolic rate more accurately than the alternatives in both non-obese and obese adults. Harris-Benedict, from 1918, is the oldest equation in common use and tends to overestimate by roughly 5% against modern measurements. Katch-McArdle uses lean body mass instead of height and sex, making it more suitable for lean or very muscular people — but it requires a measured body fat percentage, and if you leave that blank the calculator falls back to Mifflin-St Jeor and says so.

Self-reported activity level is unreliable, and the gap between adjacent categories is several hundred calories per day — moderately active (1.55) versus very active (1.725) is a meaningfully different TDEE for the same BMR. Most people overestimate their own activity level, so if your TDEE-based target isn't matching your real-world results, this is the input most worth reconsidering first.

The calculator applies a sex-specific floor — 1,200 kcal for women, 1,500 kcal for men — and won't display a target below that regardless of the goal rate you request. If your requested rate implies a lower number, the target is raised to the floor and the result explains why, since sustained intake below that level is generally recommended only under medical supervision.

Not indefinitely. A kilogram of body fat holds roughly 7,700 kcal, so a ~550 kcal/day deficit is the math behind a 0.5 kg/week estimate — but Hall and colleagues' modeling in The Lancet showed that a sustained deficit produces progressively less weight loss over time as the body adapts — the simple linear rule overpredicts long-term results. It's a reasonable starting estimate, not a guarantee that the same deficit keeps producing the same weekly loss months in.

It's built for healthy, non-pregnant adults using the number as a starting point to adjust from. It doesn't apply to children or adolescents, pregnant or breastfeeding people, anyone with a thyroid disorder or other condition that alters metabolic rate, anyone with a current or past eating disorder, or anyone already on a medically supervised diet — in each case, follow the guidance that actually accounts for your situation instead.