How TDEE is calculated
This uses the Mifflin-St Jeor equation — the most accurate common formula. First it finds your BMR (calories burned at rest):
- Men: 10×weight(kg) + 6.25×height(cm) − 5×age + 5
- Women: 10×weight(kg) + 6.25×height(cm) − 5×age − 161
Then it multiplies BMR by an activity factor (1.2–1.9) to estimate your full daily burn. Worked example: a 30-year-old woman, 65 kg, 165 cm, moderately active, has a BMR of 10×65 + 6.25×165 − 5×30 − 161 ≈ 1,370 kcal, and a TDEE of 1,370 × 1.55 ≈ 2,124 kcal/day.
Where this formula comes from
The Mifflin-St Jeor equation was published in 1990 by researchers Mark Mifflin and Sachiko St Jeor, and has since replaced the older 1919 Harris-Benedict equation as the standard in clinical dietetics because it more closely matches measured resting energy expenditure in modern populations.
Using TDEE for your goal
- Lose fat: eat ~300–500 calories below TDEE.
- Maintain: eat around TDEE.
- Build muscle: eat ~200–400 above TDEE with strength training.
Limitations
Like any predictive equation, Mifflin-St Jeor gives an estimate, not a direct measurement — actual burn can vary by roughly 10% depending on genetics, muscle mass, and thyroid function. Treat the result as a starting point, then adjust up or down based on how your weight actually trends over 2–3 weeks.
Want the breakdown into protein, carbs and fat? Use the macro calculator.