TDEE & BMR Calculator
Five published BMR equations run at once, so you can see how much they disagree instead of trusting one number in isolation.
- 01Enter age, sex, height and weight.
- 02Choose the activity level that matches a typical week, not your best week.
- 03Add body fat if you know it — this unlocks two lean-mass equations.
What the terms mean
- BMR
- Basal metabolic rate: energy used at complete rest, before any activity.
- TDEE
- Total daily energy expenditure: BMR multiplied by an activity factor.
- Activity factor
- A multiplier from 1.2 (sedentary) to 1.9 (very active).
- NEAT
- Non-exercise activity: fidgeting, walking, standing. Varies enormously between people.
Unlocks the two lean-mass equations, which are more accurate when you know it.
Using Mifflin-St Jeor — best validated when body fat is unknown.
Method & sources
Every equation here was fitted to a population sample, which is why they disagree — the 149 kcal spread above is the honest uncertainty in any prediction, not a defect. Supplying a body-fat estimate unlocks two further equations that are usually more accurate.
Mifflin MD et al., Am J Clin Nutr 1990 · Roza & Shizgal 1984 · Katch & McArdle · Cunningham JJ 1980 · Owen OE et al. 1986–87
What these numbers
actually tell you.
The spread between formulas is the real answer
Each equation was fitted to a different population sample, which is why they disagree. That spread is the honest uncertainty in any prediction of your expenditure, and no single formula is "correct". Use the recommended one as your starting figure and treat the range as the margin of error.
Which formula to trust
Without a body-fat figure, Mifflin-St Jeor is the best-validated general option. With one, the lean-mass equations (Katch-McArdle, Cunningham) usually track better, because two people at the same weight can carry very different amounts of metabolically active tissue. Cunningham reads higher and was derived in athletic populations.
Why your real TDEE probably differs
The largest uncontrolled variable is unconscious movement. Someone who takes twelve thousand incidental steps a day and someone who takes three thousand can differ by four hundred calories at identical bodyweights. If your weight is not moving as the number predicts, the number is wrong for you — not the other way round.
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