BMR vs. TDEE: What's the Difference?
If you've used a calorie calculator, you've probably seen both "BMR" and "TDEE." They sound interchangeable but mean very different things — and knowing which is which keeps you from eating far too little.
BMR: what your body burns at rest
BMR (basal metabolic rate) is the energy your body uses just to stay alive — breathing, circulating blood, keeping your organs running — if you did nothing but lie still all day. It's the floor of your metabolism, and for most people it's a surprisingly large share of total calories: often 60–70% of everything you burn.
The most trusted estimate is the Mifflin-St Jeor equation:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Estimate yours with the BMR calculator.
TDEE: what you actually burn in a day
TDEE (total daily energy expenditure) is your BMR plus everything else you do — walking, working, exercising, even fidgeting and digesting food. It's your real, all-in daily calorie burn, and it's the number that matters for managing your weight.
TDEE is calculated by multiplying BMR by an activity factor:
| Activity level | Multiplier |
|---|---|
| Sedentary (desk job, little exercise) | × 1.2 |
| Lightly active (1–3 days/week) | × 1.375 |
| Moderately active (3–5 days/week) | × 1.55 |
| Very active (6–7 days/week) | × 1.725 |
| Extremely active (physical job + training) | × 1.9 |
The TDEE calculator does both steps for you — BMR via Mifflin-St Jeor, then your activity multiplier — to give your real daily burn.
Which one should you eat to?
This is the crucial part: eat relative to your TDEE, not your BMR. Your TDEE is what you actually burn, so:
- To maintain weight: eat around your TDEE.
- To lose weight: eat below your TDEE (a 300–500 calorie deficit is a good target).
- To gain weight/muscle: eat above your TDEE.
A common and risky mistake is eating at your BMR to lose weight. Because BMR ignores all your daily activity, that creates a huge, unsustainable deficit that saps energy and burns muscle. Your BMR is useful as a reference point and a floor you generally shouldn't eat below — but your TDEE is the number your calorie goal is built around.
Medical disclaimer: These equations are estimates and individual metabolism varies. Educational information only, not medical or nutritional advice. Formula: Mifflin-St Jeor. Last reviewed: July 2026.