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:

The short version: BMR is what it costs to be alive, TDEE is what it costs to be you, and the second is the one that pays for your day.

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.

Between 20% and 90%, and which end you sit at is decided entirely by the activity level you pick. Here is one man, 30 years old, 175 cm and 70 kg, with a BMR of 1,649 kcal, at each of the five levels:

The same body, the same equation, and a 1,154 kcal spread between the top and bottom row. Nothing else you enter into a calculator comes close to that, which is why picking your activity level honestly matters more than which BMR equation the site runs.

Yes, in practice. Maintenance calories are the intake at which your weight holds steady, which is the same thing as matching what you expend in a day, which is what TDEE estimates. The two words describe the same number from different directions: TDEE from the burning side, maintenance from the eating side.

The one difference worth keeping in mind is that TDEE is a prediction from an equation, while your true maintenance level is a fact about you that only shows up in the scale over two or three weeks. If they disagree, the scale is right. Maintenance calories explained covers how to find your real figure.

It is a common plan and a poor one. Eating your BMR while living a normal day means running a deficit the size of everything above it, which for the moderately active man above is over 900 kcal a day before he has deliberately cut anything.

That is roughly double the deficit most people intend to be in, and the practical consequences are the familiar ones: hunger that does not settle, training that gets worse rather than better, and a plan abandoned inside a month. Build the target from TDEE and subtract a deliberate amount, which is what how big a calorie deficit you actually need works through.

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.