What TDEE Is Made Of
Total daily energy expenditure is everything the body burns in a day, and it has four components:
- Basal metabolic rate — 60–70% of the total. Keeping you alive at rest: organs, brain, cell repair.
- Thermic effect of food — about 10%. Digesting and absorbing what you eat. Protein costs the most to process.
- Exercise activity — 5–15% for most people. Deliberate training.
- Non-exercise activity thermogenesis — 10–30%, and highly variable. Walking, fidgeting, standing, gesturing. NEAT can differ by 2,000 calories a day between two people of the same size.
The activity multiplier in this calculator bundles the last three together, which is why picking it honestly matters more than the formula used for BMR.
TDEE Activity Chart
For a BMR of 1,755 calories:
| Activity level | Multiplier | Description | Daily calories |
|---|---|---|---|
| Sedentary | 1.200 | Desk job, little deliberate exercise | 2,106 |
| Lightly active | 1.375 | Exercise 1–3 days a week | 2,413 |
| Moderately active | 1.550 | Exercise 3–5 days a week | 2,720 |
| Very active | 1.725 | Exercise 6–7 days a week | 3,027 |
| Extremely active | 1.900 | Physical job or twice-daily training | 3,334 |
The gap between sedentary and very active is over 921 calories. Choosing the wrong level is the largest source of error in any TDEE estimate, and people almost always choose too high.
Which Formula
Mifflin-St Jeor is the default and the most accurate for the general population, typically within 10% for people of average body composition. Katch-McArdle uses lean body mass instead of total weight, which makes it better for lean, muscular or obese individuals — but it requires a body fat measurement, and a bad estimate makes it worse rather than better.
Using It for Weight Change
A pound of fat holds roughly 3,500 calories; a kilogram roughly 7,700. A 500-calorie daily deficit therefore predicts about a pound a week. In practice the loss slows, because a smaller body burns less and adaptive thermogenesis reduces NEAT.
Deficits beyond 25% of TDEE increase muscle loss without meaningfully increasing fat loss. For most people 15–20% is the sustainable range.
The Calculator Is a Starting Point
Every TDEE formula is a population estimate with individual variation of ±10–15%. The reliable method is to eat at the estimate for two to three weeks while tracking weight, then adjust by 100–200 calories based on what actually happened. The scale is more accurate than any equation.
Frequently Asked Questions
Why is my TDEE lower than my fitness tracker says?
Wrist trackers overestimate calorie burn substantially — validation studies commonly find errors of 20–90% for activity calories. They are useful for trends, not for setting intake.
Does TDEE change as I lose weight?
Yes, and it must be recalculated. A smaller body needs less energy, which is why a deficit that worked initially stops working after 10–15 pounds.
Should I eat back exercise calories?
Not if your activity multiplier already includes the exercise — that would count it twice. This is the most common error in combining a TDEE estimate with an activity tracker.