TDEE & BMR Calculator
Free TDEE (Total Daily Energy Expenditure) and BMR calculator — uses the Mifflin-St Jeor equation, the formula clinical dietitians prefer. Metric units (kg, cm). Runs in your browser.
Type in your sex, weight, height, age and activity level. The calculator returns your BMR (basal metabolic rate — energy at complete rest) and your TDEE (total daily energy expenditure — what you actually need to eat to maintain weight).
The formulas
BMR via Mifflin-St Jeor, the equation modern clinical practice prefers:
Male: BMR = 10·W + 6.25·H − 5·A + 5
Female: BMR = 10·W + 6.25·H − 5·A − 161
W = weight in kg, H = height in cm, A = age in years.
TDEE multiplies BMR by an activity factor:
| Activity | Multiplier |
|---|---|
| Sedentary | 1.2 |
| Light | 1.375 |
| Moderate | 1.55 |
| Active | 1.725 |
| Very active | 1.9 |
So for a 80 kg, 180 cm, 30-year-old man:
BMR = 10·80 + 6.25·180 − 5·30 + 5 = 1,780 kcal/day. At “moderate” activity
(1.55), TDEE ≈ 2,759 kcal/day.
Using the result
- Maintenance: eat ≈ TDEE.
- Weight loss: eat below TDEE. A 500 kcal/day deficit averages ~0.5 kg/week of weight loss over time. Bigger deficits work faster but cost more lean mass and are harder to stick to.
- Weight / muscle gain: eat 200–500 kcal/day above TDEE, alongside resistance training.
Treat the number as a starting point. Weigh yourself daily (or every other day) for two or three weeks, look at the trend (not any one reading), and adjust calories up or down by 100–200 kcal until the trend matches your goal.
Why Mifflin-St Jeor
The older Harris-Benedict equation (1919) systematically overestimates BMR on modern bodies because nutrition and lean-mass distribution have shifted in a century. Mifflin-St Jeor was developed in 1990 on a contemporary population and predicts measured BMR within ~10% for most adults.
When this isn’t accurate
For very obese individuals, Mifflin-St Jeor overestimates BMR (fat is less metabolically active than lean tissue, so a high-BMI person carries proportionally more “cheap” mass). For very lean athletes with high lean mass, it can underestimate. The Katch-McArdle formula, which uses lean mass directly, is more accurate if you have a reliable body-fat measurement.
Worked examples
-
Male, 80 kg, 180 cm, 30 yrs, moderate activity
BMR: 1,780 kcal/day — TDEE 2,759 kcal/day at this activity level.
-
Female, 65 kg, 165 cm, 28 yrs, sedentary
BMR: 1,380 kcal/day — TDEE 1,656 kcal/day at this activity level.
Frequently asked questions
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the energy your body burns at complete rest, just to keep organs running — about 60–70% of total daily expenditure for most people. TDEE (Total Daily Energy Expenditure) is BMR plus everything else: digestion, fidgeting, walking around, formal exercise. TDEE is what you actually eat to maintain weight.
Which formula does this use?
Mifflin-St Jeor, the equation most clinical dietitians prefer today (Am J Clin Nutr 1990). It's more accurate than the older Harris-Benedict on modern bodies. BMR for men is 10·W + 6.25·H − 5·A + 5; for women 10·W + 6.25·H − 5·A − 161 (W kg, H cm, A years).
How accurate are the activity multipliers?
Approximate. The PAL (physical activity level) multipliers — 1.2, 1.375, 1.55, 1.725, 1.9 — come from ACSM / FAO guidelines and are population averages. Real-world expenditure varies ±15% even for people in the same activity bucket. Use TDEE as a starting point; track weight over 2–3 weeks and adjust calories up or down based on actual results.
How do I use this for weight loss or gain?
Maintenance is TDEE. For weight **loss**, eat below it — a 500 kcal/day deficit averages roughly 0.5 kg/week of fat loss; bigger deficits accelerate loss but are harder to sustain and tend to cost lean mass. For **gain** (muscle building), eat 200–500 kcal/day above TDEE alongside resistance training.
Does this work for very lean or very heavy people?
Mifflin-St Jeor is fairly robust across normal BMI ranges but tends to overestimate BMR for very high body-fat individuals (because fat tissue is less metabolically active than lean tissue). Athletes with very high lean mass may be underestimated for the same reason. If you have an unusual body composition, a body-fat-adjusted formula (Katch-McArdle) is more accurate.
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