TDEE Calculator
Your Total Daily Energy Expenditure — the calories you actually burn in a day — using the Mifflin-St Jeor equation, the formula with the best track record in validation studies.
Your numbers
Formula: Mifflin-St Jeor. These are starting points — adjust after 2–3 weeks of real-world results.
What TDEE actually is
TDEE is everything your body burns in a day: the energy needed just to stay alive (your BMR — roughly 60–70% of the total for most people), the cost of digesting food (about 10%), deliberate exercise, and all the incidental movement in between — walking to the car, fidgeting, taking the stairs. That last category, called NEAT, varies enormously between people and is why two people the same size can have very different maintenance calories. If you're not sure of the difference between the two headline numbers, our article on TDEE vs. BMR untangles them.
The formula this calculator uses
The Mifflin-St Jeor equation estimates BMR from weight, height, age, and sex:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
BMR is then multiplied by an activity factor from 1.2 (sedentary) to 1.9 (extremely active). Mifflin-St Jeor is used here rather than the older Harris-Benedict equation because validation studies have repeatedly found it more accurate for modern populations — Harris-Benedict was derived in 1919 and tends to overestimate by around 5%.
Worked example
A 35-year-old man, 5'10" (178 cm), 180 lb (81.6 kg): BMR = 10 × 81.6 + 6.25 × 178 − 5 × 35 + 5 = 1,754 calories. If he trains 3–5 days a week (factor 1.55), TDEE = 1,754 × 1.55 ≈ 2,719 calories. To lose about a pound a week he'd eat around 2,200; to gain slowly, around 2,950–3,000.
The two mistakes that break TDEE numbers
Overstating activity level. "Moderately active" means genuinely training 3–5 days a week, not owning a gym membership. A desk worker who lifts twice a week is "lightly active" at best. Choosing one level too high inflates the estimate by 300–400 calories — enough to erase an intended deficit entirely.
Treating the number as truth instead of a starting point. Any formula has an error band of ±10% or so for an individual. The fix is empirical: eat your calculated target consistently for two to three weeks, track your weight as a weekly average (daily weights swing too much with water), and adjust by 100–200 calories based on what actually happens. Your real TDEE is the number at which your weekly average holds steady.
Questions people ask
Why is my TDEE lower than my fitness tracker says?
Wrist trackers routinely overestimate exercise burn — often by 20–40% in accuracy studies. When the two disagree, trust the formula plus real-world weight trends over the watch.
Does TDEE drop as I lose weight?
Yes, for two reasons: a lighter body costs less to run, and prolonged dieting slightly reduces NEAT. Recalculate every 10–15 lb of change. This is also why a fixed deficit produces slowing loss over time — see what's a safe calorie deficit for how to set the size sensibly.
Should I eat below my BMR?
Almost never. BMR is what a coma patient burns; you burn more by existing upright. Very-low-calorie diets under medical supervision aside, aggressive deficits mostly produce muscle loss, misery, and rebound.