Estimates only, not medical advice. These are population formulas, and any one person can be well above or below them. If you are pregnant or breastfeeding, under 18, have diabetes, kidney disease, an eating disorder or another medical condition, or take medicine that affects weight, talk to your doctor or a registered dietitian before changing how you eat.
How TDEE is worked out
TDEE is your basal metabolic rate (BMR), the calories you burn lying still, multiplied by an activity factor. This calculator runs three published BMR equations so you can see how much they agree, then applies the same activity factor to each.
Mifflin-St Jeor: 10W + 6.25H − 5A + 5 (men) or − 161 (women)
Harris-Benedict, revised: men 88.362 + 13.397W + 4.799H − 5.677A; women 447.593 + 9.247W + 3.098H − 4.330A
Katch-McArdle: 370 + 21.6 × lean mass, where lean mass = W × (1 − body fat %)
TDEE = BMR × activity factor
W = weight in kg, H = height in cm, A = age in years
- Mifflin-St Jeor comes from a 1990 study of 498 adults measured by indirect calorimetry. It is the main result here because a 2005 systematic review found it the most likely to land within 10% of measured resting calories.
- Harris-Benedict dates from 1919. We use the version re-fitted by Roza and Shizgal in 1984, which is the one most calculators mean when they say Harris-Benedict.
- Katch-McArdle uses lean body mass instead of age and sex, so it only appears when you enter a body fat percentage. It is a textbook formula from exercise physiology; we could not find a single original paper for it, so treat it as a cross-check.
Worked example: a 30-year-old man, 5 ft 10 in, 180 lb, 18% body fat
180 lb is 81.65 kg and 5 ft 10 in is 177.8 cm. He exercises 1 to 3 days a week, so the factor is 1.375.
| Formula | BMR | × 1.375 = TDEE |
|---|---|---|
| Mifflin-St Jeor: 816.5 + 1,111.3 − 150 + 5 | 1,783 | 2,451 |
| Harris-Benedict: 88.4 + 1,093.8 + 853.3 − 170.3 | 1,865 | 2,565 |
| Katch-McArdle: 370 + 21.6 × 66.95 kg lean | 1,816 | 2,497 |
The three answers sit within about 115 calories of each other, which is typical. His BMI is 25.8, just into the overweight band, but at 18% body fat that says more about muscle than fat, one of the reasons the BMI calculator explains its limits. This example is loaded when the page opens.
Activity factors
| Level | What it looks like | Factor |
|---|---|---|
| Sedentary | Desk job, little planned exercise | 1.2 |
| Lightly active | Exercise 1 to 3 days a week | 1.375 |
| Moderately active | Exercise 3 to 5 days a week | 1.55 |
| Very active | Hard exercise 6 to 7 days a week | 1.725 |
| Extra active | Physical job plus hard training | 1.9 |
These five factors are a convention used by nearly every TDEE calculator, and we could not trace them to one original study. They fall inside the physical activity level (PAL) bands the Institute of Medicine used for its dietary reference intakes, from about 1.0–1.39 for sedentary up to 1.9–2.49 for very active (table in BMC Public Health).
Limits
- Expect an error of 10% or more for any one person. Check the estimate against your weight over 2 to 3 weeks.
- The 2005 review noted that older adults and US ethnic minorities were under-represented in the studies behind these equations, so they may fit those groups less well.
- Body fat from home scales can be several points off. A wrong body fat figure makes Katch-McArdle worse, not better.
- For adults 18 and over only, and not for pregnancy or breastfeeding.
To turn your TDEE into a daily target, use the calorie calculator or the calorie deficit calculator.
Sources checked October 2026.
Questions people ask
What is TDEE?
TDEE stands for total daily energy expenditure: all the calories you burn in a day. It is your resting burn (BMR) plus the energy for digesting food, everyday movement and exercise. If you eat about your TDEE, your weight should stay roughly the same.
Which TDEE formula is the most accurate?
For most adults, Mifflin-St Jeor. A 2005 systematic review by Frankenfield and colleagues found it came within 10% of measured resting calories for more people than the Harris-Benedict and other equations. Katch-McArdle may suit lean, muscular people as a cross-check, but only if your body fat percentage is accurate.
Why do the three formulas give different answers?
They were fitted to different groups of people in different decades. The revised Harris-Benedict equation (Roza and Shizgal, 1984) tends to give a slightly higher number than Mifflin-St Jeor (1990). Katch-McArdle ignores age and sex and uses lean mass only. The spread between them is a fair picture of how uncertain any single estimate is.
Which activity level should I pick?
Pick the level that matches a normal week, not your best week. Sedentary (× 1.2) is a desk job with little planned exercise. Lightly active (× 1.375) is exercise 1 to 3 days a week, moderately active (× 1.55) is 3 to 5 days, very active (× 1.725) is hard exercise 6 to 7 days, and extra active (× 1.9) is a physical job plus hard training. If you are torn between two, choose the lower one.
Do fitness trackers measure TDEE better?
Wrist trackers estimate calories burned from heart rate and movement, so they are estimates too, just like a formula. Neither one measures your real burn. The most reliable check is your own weight trend: if it holds steady over 2 to 3 weeks while you eat a known amount, that amount is close to your TDEE.
How do I use my TDEE to lose weight?
Eat less than your TDEE. About 500 calories a day under it gives roughly 1 lb a week. The calorie deficit calculator turns that into a daily target and a goal date, and it will not go below 1,200 calories for women or 1,500 for men.