BMR is what your body spends at complete rest. TDEE is BMR multiplied by an activity factor between 1.2 and 1.9 — that is the number to eat against. For most adults TDEE lands between 1,600 and 3,000 kcal a day.
The three published equations disagree with each other by 100–200 kcal for the same person, which is a fair measure of how exact any prediction can be. This page shows all three rather than picking one for you.
A worked example
Nothing filled in yet, so this is an average 35-year-old woman of median US height and weight, moderately active. Put your own figures in the form above and every table below recalculates.
TDEE at every activity level
Most people overestimate this. The honest question is not what a good week looks like but what a typical one does.
| Activity level | A typical week | Factor | TDEE |
|---|---|---|---|
| Sedentary | Desk work, little or no exercise | 1.2 | 1,737 |
| Lightly active | Light exercise 1–3 days a week | 1.375 | 1,990 |
| Moderately active ← | Exercise 3–5 days a week | 1.55 | 2,243 |
| Very active | Hard exercise 6–7 days a week | 1.725 | 2,496 |
| Extra active | Physical job or training twice a day | 1.9 | 2,750 |
The three formulas, side by side
Same body, three published equations. The gap between them is the honest error bar on any prediction.
| Formula | BMR | TDEE at your level | Notes |
|---|---|---|---|
| Mifflin–St Jeor | 1,447 | 2,243 | Default. Best general performance of the three. |
| Harris–Benedict | 1,512 | 2,344 | Oldest; tends to read slightly high. |
| Katch–McArdle | Needs a body-fat percentage — add one above | Needs body fat %; ignores sex, uses lean mass. | |
Katch–McArdle is missing a body-fat percentage, so it fell back to a default. Add yours above and it becomes the most accurate of the three for you.
Cut, maintain, bulk
Three bands off the same maintenance figure. These are targets, not instructions — read the safety note below before acting on the lower one.
| Band | Calories a day | Change from maintenance | Expected pace |
|---|---|---|---|
| Aggressive cut | 1,794 | −449 kcal | 0.9 lb / week |
| Steady cut | 1,907 | −336 kcal | 0.67 lb / week |
| Gentle cut | 2,019 | −224 kcal | 0.45 lb / week |
| Maintain | 2,243 | — | holds |
| Lean bulk | 2,467 | +224 kcal | 0.45 lb / week |
| Faster bulk | 2,580 | +337 kcal | 0.67 lb / week |
What BMR and TDEE actually mean
Basal metabolic rate is the energy your body spends staying alive with no movement at all: keeping your heart going, your brain running and your temperature steady. For most adults it accounts for 60–70% of everything they burn in a day, which is why it dominates the total even for people who train hard.
Total daily energy expenditure is BMR plus everything else — moving around, digesting food, deliberate exercise. It is the number worth eating against, and it is the one that moves week to week depending on how much you actually did.
Why the activity multiplier is where estimates go wrong
The BMR equations are reasonably well behaved. The multiplier is not: the step from "lightly active" to "moderately active" is worth several hundred calories a day, and people pick the flattering one. Three gym sessions a week around a desk job is lightly active, not moderate — the desk is most of the week.
If your weight is not doing what the number predicts after a fortnight, the multiplier is the first thing to move, not the formula.
What BMI does and does not tell you
BMI is weight divided by height squared, and that is the whole of it. It says nothing about how much of that weight is muscle, so a lifter and a sedentary person of the same weight and height get the same figure. It is a population screening tool that happens to be easy to compute, not a measure of an individual's health.
It is included here because people look for it alongside TDEE, and because a value well below 18.5 is a genuine reason to stop and talk to a doctor before cutting calories.
Please read. These numbers are estimates for healthy adults. They are not appropriate as targets during pregnancy or breastfeeding, under 18, or alongside a condition that affects metabolism or appetite — talk to a doctor or a registered dietitian instead. If calorie counting is making your relationship with food worse, that is reason enough to stop; in the US the National Alliance for Eating Disorders helpline is 1-866-662-1235. Nothing here is medical advice; see our health disclaimer.
You can earn the full version instead of paying for it
Knowing the number is the easy half. The half that changes anything is logging against it every day, and that costs nothing here — no card, no charges, no end date.
- Create an account and log a few meals. New accounts open with a two-day Plus trial — three days if somebody invited you — and then settle onto the free plan: no card, no end date, one meal scan a day.
- Publish an honest post, story, write-up or short video about what you found — or invite three people who go on to actually use it.
- Send us the link. A published piece unlocks the higher tier; three qualified invites unlock 90 days of the full version.
Your post has to say you got free access in exchange — that is an FTC requirement in the United States. Access is granted whether what you write is positive or critical. Full terms: promotional access.