Work out your total daily energy expenditure — the calories you burn on an average day. It is the number every diet and every surplus is built on. Estimated with the Mifflin-St Jeor equation, the most widely validated formula for healthy adults.
Estimate, not a measurement — typical error is around 10%. Adjust from it using your own results over two to three weeks.
Track it automatically in Vitalis →First we estimate your basal metabolic rate with the Mifflin-St Jeor equation, published in 1990 and still the formula most clinical guidelines recommend for healthy adults:
Then we multiply by an activity factor — 1.2 for sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extremely active — to get TDEE. Those multipliers come from the physical activity levels used in the ACSM guidance and the Harris-Benedict tradition.
We deliberately do not use the Katch-McArdle equation, which needs a lean-mass figure. Most people do not have an accurate one, and feeding a guessed body-fat percentage into a more precise formula does not make the result more precise.
TDEE is maintenance — eat that much and your weight stays put over weeks. Everything else is a percentage of it. Fat loss at 15–20% below; muscle gain at 5–15% above. The table on the right uses the middle of those ranges.
The single most useful thing you can do with this number is treat it as a hypothesis. Eat at your estimate for two weeks, weigh yourself daily under the same conditions, and compare the seven-day averages. If the average is flat when you expected a loss, your true TDEE is lower than the formula said — and now you know by how much.
A 32-year-old man, 180 cm, 80 kg, trains 4×/week. BMR = 10(80) + 6.25(180) − 5(32) + 5 = 1,780. At a moderate factor of 1.55, TDEE ≈ 2,759 kcal. A 20% deficit is 2,207 kcal.
A 28-year-old woman, 165 cm, 62 kg, desk job, 2×/week. BMR = 10(62) + 6.25(165) − 5(28) − 161 = 1,350. At a light factor of 1.375, TDEE ≈ 1,856 kcal. A 10% surplus is 2,042 kcal.
A 45-year-old man, 175 cm, 95 kg, sedentary. BMR = 10(95) + 6.25(175) − 5(45) + 5 = 1,809. At 1.2, TDEE ≈ 2,171 kcal. Note the estimate is probably high here — Mifflin-St Jeor overestimates at higher body fat, which is why the adaptive approach matters more than the formula in this case.
BMR (basal metabolic rate) is what you burn at complete rest — keeping your heart beating, your lungs working, your body at temperature. TDEE (total daily energy expenditure) is BMR plus everything else: moving around, digesting food, and training. BMR is usually 60–70% of TDEE.
For most people, within about 10% — so on a 2,500 kcal estimate, expect the true figure to sit somewhere between 2,250 and 2,750. Accuracy drops at the extremes: very high muscle mass pushes the estimate low, very high body fat pushes it high. Treat the number as a starting point to adjust from, not a measurement.
Pick the one that matches your average week, not your best week. Most people overestimate here. If you train four times a week but sit at a desk for nine hours a day, 'moderately active' is usually closer than 'very active'. If you are unsure between two, start with the lower one and adjust after two weeks of data.
Body mass, muscle mass, activity and even sleep and stress all move it. Losing 5 kg lowers TDEE by roughly 100 kcal. A long diet can also lower it more than weight loss alone explains — the adaptive component. That is why re-estimating every few weeks matters.
No — TDEE is maintenance. A common starting point for fat loss is 15–20% below TDEE, which typically gives 0.5–1% of body weight lost per week. Larger deficits work faster but are harder to sustain and cost more muscle. The table above shows the standard percentages.
Less well. Mifflin-St Jeor uses total body weight and does not know how much of it is muscle. For very muscular people it tends to underestimate; for very high body fat it tends to overestimate. In both cases, an adaptive estimate — back-calculated from what you actually ate and how your weight actually moved — is more reliable once you have three or four weeks of consistent data.
This calculator is an estimate for healthy adults and is not medical advice. If you are pregnant, managing a chronic condition, or under 18, talk to a professional before changing your intake. Full health disclaimer.