BMR vs TDEE: what's the difference?

Basal Metabolic Rate is the energy your body spends doing nothing at all: breathing, circulating blood, maintaining temperature, repairing cells. It is measured at complete rest, in a fasted state, and for most adults it accounts for the majority of daily energy use, typically somewhere around 60–70% of the total.

That last point surprises people. The bulk of what you burn is not exercise; it is the cost of being a living body. This is also why BMR scales with size: a larger body has more tissue to keep running, which is why weight and height both appear in the equation.

Total Daily Energy Expenditure is BMR plus everything else: walking to the kitchen, standing at a desk, training, fidgeting, and the energy spent digesting food. In practice, calculators do not measure those separately; they take your BMR and multiply it by a single activity factor that stands in for the whole lot.

FitQuota uses the standard five-level scale, and the spread between the ends of it is large:

Take a 32-year-old man, 175 cm and 70 kg. The Mifflin-St Jeor equation gives:

BMR = (10 × 70) + (6.25 × 175) − (5 × 32) + 5 = 1,639 kcal

That is his resting figure. If he is moderately active, his TDEE is that number scaled by 1.55:

TDEE = 1,639 × 1.55 = 2,540 kcal

The gap is just over 900 kcal, which is the whole point. Setting a calorie target from 1,639 instead of 2,540 would put him in a deficit roughly twice as steep as he intended, before he had cut a single thing from his diet.

Use TDEE. It is the one that describes your actual day, and it is the number a calorie target should be built from, whether for maintenance, deficit or surplus.

BMR is still worth knowing for two reasons. It tells you how much of your expenditure is fixed rather than earned, which reframes how much a single workout really moves the total. And it acts as a floor: an intake below your BMR is worth a second look, since that is less energy than your body uses before you get out of bed.

You can run both on this site: the BMR Calculator and the TDEE Calculator share one implementation, so the BMR shown on both pages is the same number rather than two independent estimates that happen to be close.

Nearly, and the two get used interchangeably. Resting Metabolic Rate is measured under less strict conditions than true basal rate, and comes out slightly higher, usually by a few percent. The difference matters in a metabolic ward and almost never matters for setting a calorie target, so a calculator labelled either way is estimating the same thing for your purposes.