TDEE Calculator
TDEE is every calorie you burn in a day — resting metabolism plus movement plus digestion. Knowing it turns weight change from guesswork into arithmetic, because a deficit or surplus is measured against this number, not against a generic 2,000.
About You
Mifflin-St Jeor is the equation clinical dietitians use as default.
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BMR, TDEE and why the difference matters
BMR is what you would burn lying still all day — keeping a heart beating, a brain running, a temperature held. It is typically 60–70% of total expenditure. TDEE multiplies BMR by an activity factor to include movement, exercise and the energy cost of digesting food.
Diet advice built on a flat 2,000 calories ignores that a 95 kg active man and a 55 kg sedentary woman differ by well over a thousand calories a day. Deficits only mean something relative to your own TDEE.
Why Mifflin-St Jeor
Harris-Benedict, published in 1919 and revised in 1984, overestimates for most modern populations. Mifflin-St Jeor (1990) was validated against indirect calorimetry and is the equation the Academy of Nutrition and Dietetics recommends as default. Katch-McArdle is more accurate still, but requires a measured body fat percentage most people do not have.
Any equation is an estimate with roughly ±10% error. Use it as a starting point, then adjust on two weeks of real weight data.
Setting the rate honestly
0.5–1% of body weight per week is the range that preserves muscle while losing fat. Faster is possible and mostly costs you lean mass and adherence. For muscle gain the sustainable figure is far lower — roughly 0.25–0.5% per week — because the body can only build tissue so quickly, and anything beyond that is fat.
The 3,500-calorie rule is an approximation
One pound of fat stores roughly 3,500 calories, which is where the rule comes from. It holds reasonably in the short term, but as weight falls so does TDEE, so a fixed deficit produces slowing loss. Recalculate every 4–5 kg.