Quick answer: This tdee calculator uses the Mifflin-St Jeor BMR equation: TDEE (Total Daily Energy Expenditure) = BMR × activity factor (1.2 for sedentary up to 1.9 for extra active). It is the calories you burn in a full day. Eat below it to lose weight, at it to maintain, above it to gain.
Last reviewed: September 2026
Key facts
- TDEE = BMR × activity factor (1.2 sedentary → 1.9 extra active).
- Your TDEE is your maintenance calories — eat exactly this to hold your weight.
- A daily deficit of ~500 kcal loses roughly 0.5 kg per week.
- BMR is 60–70% of TDEE; activity and digestion make up the rest.
- BMR is estimated with the Mifflin-St Jeor equation (men: 10W + 6.25H − 5A + 5; women: − 161 instead of + 5).
This free tdee calculator estimates your Total Daily Energy Expenditure from the Mifflin-St Jeor BMR equation times your activity level, in metric or imperial units. Get your maintenance calories plus tailored targets for losing, maintaining or gaining weight. Results update live as you change any input below.
TDEE is the single most useful number in any diet plan: it turns vague "eat less" advice into an exact daily calorie target. Results update live as you change any input.
What is TDEE?
Total Daily Energy Expenditure is everything your body burns in 24 hours, measured in kilocalories (kcal). It has three components:
| Component | Share of TDEE | What it is |
|---|---|---|
| Basal metabolic rate (BMR) | 60–70% | Energy to keep you alive at rest: heartbeat, breathing, brain, body heat. |
| Thermic effect of food (TEF) | ~10% | Energy spent digesting and absorbing meals; protein costs the most to process. |
| Activity thermogenesis | 15–30% | Everything you do: exercise (EAT) plus daily movement like walking and fidgeting (NEAT). |
BMR dominates, which is why this tdee calculator starts from a BMR equation and scales it by an activity factor rather than trying to count every step.
Background: a century of calorie equations
The formulas behind this calculator come from a hundred years of metabolic research. In 1919, J. Arthur Harris and Francis G. Benedict published landmark BMR equations from Carnegie Institution studies of 239 subjects. In 1984, Roza and Shizgal revised the Harris-Benedict constants with newer data.
The equation this calculator uses came later: in 1990, Mifflin, St Jeor and colleagues published "A new predictive equation for resting energy expenditure in healthy individuals" in the American Journal of Clinical Nutrition, derived from 498 healthy subjects. Systematic reviews (notably Frankenfield et al., 2005) found Mifflin-St Jeor the most accurate BMR predictor for most adults, which is why dietitians and fitness tools default to it. A third option, the Katch-McArdle formula, skips age and height and uses lean body mass instead — better for very muscular people, but only if you know your body-fat percentage. The 1.2–1.9 activity multipliers trace back to the same Harris-Benedict tradition, refined by later physical-activity-ratio research (Black et al., 1996).
How to use this tdee calculator
- Enter your sex, age, weight and height (metric or imperial).
- Choose the activity level that matches a typical week — be honest.
- Read your TDEE (maintenance calories) and the goal targets below it.
- Pick a goal row and eat at that calorie level for 2–3 weeks, then adjust.
How TDEE is calculated
| Activity level | Factor | Meaning |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise. |
| Lightly active | 1.375 | Light exercise 1–3 days/week. |
| Moderately active | 1.55 | Moderate exercise 3–5 days/week. |
| Very active | 1.725 | Hard exercise 6–7 days/week. |
| Extra active | 1.9 | Very hard exercise, physical job or twice-daily training. |
BMR equations compared
Three BMR formulas dominate the literature. For the same man (30 years, 80 kg, 175 cm) they give:
| Equation | Formula (men) | BMR for 80 kg / 175 cm / 30 y |
|---|---|---|
| Mifflin-St Jeor (1990, this calculator) | 10W + 6.25H − 5A + 5 | 1,749 kcal |
| Harris-Benedict (revised 1984) | 88.362 + 13.397W + 4.799H − 5.677A | 1,830 kcal |
| Katch-McArdle | 370 + 21.6 × lean mass (kg) | 1,774 kcal at 65 kg lean mass |
For women, Mifflin-St Jeor ends in − 161 instead of + 5, and Harris-Benedict uses 447.593 + 9.247W + 3.098H − 4.330A. The equations agree within ~5% for average adults and diverge for the very lean, very muscular or very heavy — where Katch-McArdle (fed with a real lean-mass number) is the better pick.
Worked examples
Man, 30, 80 kg, 175 cm, moderately active
BMR = (10 × 80) + (6.25 × 175) − (5 × 30) + 5 = 1,749 kcal. TDEE = 1,749 × 1.55 = 2,711 kcal/day.
Weight-loss target: 2,711 − 500 = 2,211 kcal/day.
Woman, 30, 65 kg, 165 cm, lightly active
BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 1,370 kcal. TDEE = 1,370 × 1.375 = 1,884 kcal/day.
Weight-gain target: 1,884 + 300 = 2,184 kcal/day.
Setting your calorie goal
| Goal | Daily intake | Expected rate |
|---|---|---|
| Fat loss | TDEE − 300 to 500 kcal | ~0.3–0.5 kg/week |
| Maintain | TDEE | Weight stable |
| Muscle gain | TDEE + 250 to 500 kcal | ~0.25–0.5 kg/week |
The 3,500 kcal rule, honestly
The "500 kcal deficit = 0.5 kg per week" rule comes from researcher Max Wishnofsky (1958): about 3,500 kcal of stored energy per 0.45 kg of body fat, so 500 × 7 ÷ 3,500 ≈ 0.45 kg/week. It is a useful starting target, not a law. Real weight loss slows over time: a lighter body has a lower TDEE, metabolic adaptation trims expenditure further, and the NIH's body-weight models show the curve flattening exactly as people observe. Treat the first 2–3 weeks as calibration — if your weight moves faster or slower than the table predicts, recalculate your TDEE and adjust the target.
Limitations
- Estimates, not measurements: expect roughly ±10% error; only lab calorimetry measures true expenditure.
- Body composition matters: two people at 80 kg can have very different BMRs if one is muscular and the other is not — muscle burns more at rest than fat.
- Activity is self-reported: most people overestimate it; when in doubt, pick the lower level.
- Not for medical edge cases: pregnancy, breastfeeding, thyroid disorders, fever, injury recovery and some medications shift expenditure beyond what the equations model.
- Children and older adults: the equations are validated for adults roughly 18–80; the calculator accepts ages 10–100 but treat out-of-range results as rough.
Frequently asked questions
Is TDEE the same as maintenance calories?
Yes. TDEE estimates everything you burn in a day, so eating exactly your TDEE keeps your weight stable. That is why it is called your maintenance level.
How accurate is a TDEE calculator?
Within roughly ±10% for most people. The Mifflin-St Jeor BMR base is well validated; the main uncertainty is your true activity level. Track weight for 2–3 weeks and adjust if it moves unexpectedly.
Why am I not losing weight at a 500 kcal deficit?
Usually the activity level was overestimated, or food intake undercounted — both are common. Re-check portions, verify your activity choice, and give it 3 weeks before changing the target.
Should I eat back exercise calories?
No — exercise is already inside your activity factor. Eating back burned calories usually double-counts them and erases the deficit.
Does TDEE change as I lose weight?
Yes. A lighter body burns fewer calories, so your TDEE falls as you lose weight. Recalculate every 5 kg lost or every few months.
Sources
- PubMed (Mifflin et al., 1990) — The original Mifflin-St Jeor resting energy expenditure paper, Am J Clin Nutr
- NIH — Energy expenditure and weight management references
- OpenStax Anatomy & Physiology — Metabolic rate and energy balance
- ACE Fitness — Activity factors and calorie goal guidance
Key takeaways
- TDEE = BMR × activity factor (1.2–1.9); this tdee calculator uses Mifflin-St Jeor for the BMR.
- Eat at TDEE to maintain, 500 under to lose, 300 over to gain.
- Be honest about activity level — it is the biggest error source.
- Expect ~±10% error; muscular or very heavy bodies diverge more.
- Recalculate as your weight changes; weight loss slows as TDEE falls.
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