What is TDEE?
TDEE stands for Total Daily Energy Expenditure — the number of calories your body burns in a 24-hour day, including basal metabolism, activity, exercise, and the energy used to digest food. It's the most useful single number for any nutrition decision: eat at your TDEE to maintain weight, eat below it to lose, eat above it to gain. Most diet and fitness recommendations are really just rules about how much to deviate from your TDEE and for how long.
For a typical sedentary adult woman, TDEE is around 1,800 kcal/day. For a moderately active man, it's closer to 2,800. The range across the adult population is enormous — a small inactive person and a large active one can differ by more than 1,500 kcal/day, which is why generic "eat 2,000 kcal" recommendations aren't useful. The TDEE Calculator gives you a personalized number based on your specific body composition and activity.
How to use the TDEE Calculator
The calculator has five inputs and shows you all your numbers at once.
- Pick units. Metric (kg + cm) or imperial (lb + ft+in). The toggle preserves your entered values, so switching mid-input doesn't lose anything.
- Select sex. Male or female — this changes a constant in the BMR formula (Mifflin-St Jeor uses +5 for men and −161 for women, reflecting average lean-mass differences).
- Enter age, height, and weight. Use whole years for age. Decimals are fine for height and weight.
- Pick your activity level. Five options from Sedentary (×1.2) to Extra Active (×1.9), each with the multiplier shown so you know what's being applied.
- Read the results. BMR and TDEE appear in the top row. Below them, three goal-based calorie targets — cut, maintain, bulk — with weekly weight-change estimates.
Output updates as you type — there's no Calculate button. Each number has a Copy button so you can paste it into a fitness tracker, a spreadsheet, or a note.
The formula behind TDEE
TDEE is calculated in two steps: first compute BMR (Basal Metabolic Rate — what your body burns at complete rest), then multiply by an activity factor.
Mifflin-St Jeor (the formula this tool uses):
Male BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Female BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
TDEE = BMR × activity multiplier
Worked example: a 30-year-old man, 180 cm tall, 80 kg, moderately active.
- BMR = 10×80 + 6.25×180 − 5×30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day
- TDEE = 1,780 × 1.55 = 2,759 kcal/day
This calculator uses Mifflin-St Jeor (1990) by default because it's been validated against indirect calorimetry — the gold-standard direct measurement of metabolic rate — more accurately than the older Harris-Benedict equation. The American Dietetic Association's 2005 review concluded Mifflin-St Jeor is the most accurate predictor of resting metabolic rate in healthy non-obese adults. The Katch-McArdle formula (which uses lean body mass instead of total weight) can be more accurate for people who know their body fat percentage — that's a v2 feature.
Activity multipliers explained
The five activity levels aren't arbitrary — they map to different real-world energy expenditures researched in nutrition literature. Pick the one that matches your typical week, not your best week.
| Level | Multiplier | What it means |
|---|---|---|
| Sedentary | ×1.2 | Desk job, no structured exercise, daily steps usually under 5,000 |
| Lightly Active | ×1.375 | Light exercise 1–3 days/week, OR a moderately active job (teacher, nurse) |
| Moderately Active | ×1.55 | Moderate exercise 3–5 days/week (running, lifting, cycling) |
| Very Active | ×1.725 | Hard exercise 6–7 days/week, sometimes twice a day |
| Extra Active | ×1.9 | Hard exercise + a physically demanding job (construction, farming, athlete in training) |
Most people overestimate their activity level. A useful rule: if you spend most of your day sitting (work, commute, evenings), you're probably Sedentary or Lightly Active even if you go to the gym a few times a week. Over 70% of US adults fall in the Sedentary or Lightly Active buckets according to physical-activity surveys.
Cut, maintain, bulk — what the goal targets mean
Below your BMR and TDEE, the calculator shows three goal-based calorie targets:
- Cut: TDEE − 500 kcal/day. The 500 kcal deficit is roughly 1 lb (0.5 kg) of fat per week, since 3,500 kcal ≈ 1 lb of body fat. This is the standard, sustainable rate of fat loss for most people.
- Maintain: Eat at your TDEE. Used in body recomposition (gaining muscle while losing fat), maintenance after a cut, or just steady-state living.
- Bulk: TDEE + 500 kcal/day. Roughly 1 lb of weight gain per week — though for muscle gain specifically, a smaller surplus (200–300 kcal/day) typically minimizes fat gain.
The 500 kcal/day rule is an approximation. Aggressive cuts (>750 kcal/day deficit) accelerate fat loss but increase muscle loss risk and rebound likelihood. Slow cuts (250 kcal/day) are easier to sustain but require longer adherence. Pick the deficit you can maintain for 8+ weeks, not the steepest one.
Limitations and edge cases
TDEE calculations have an inherent uncertainty of about ±10%. The math is precise; the real world isn't.
- Genetics shift baseline metabolism by 5–10% — some people genuinely burn more or less than the formulas predict.
- Body composition matters more than total weight. Two people of the same weight but different body-fat percentage have different metabolic rates (lean tissue burns more at rest). Mifflin-St Jeor doesn't account for this — Katch-McArdle does, but it requires a body-fat measurement.
- Adaptive thermogenesis — when you sustain a calorie deficit, your body lowers TDEE by 5–15% to defend body weight. After several weeks of dieting, you may need to recalculate at a lower body weight to keep losing.
- Activity tracking is rarely accurate. Fitness trackers overestimate calories burned by 20–40% in many studies. Use the activity-multiplier approach instead of relying on tracker numbers.
- Pregnancy, lactation, thyroid disorders, and some medications alter metabolism enough that these formulas shouldn't be relied on. Talk to a doctor or registered dietitian.
Practical advice: use the calculated TDEE as a starting point, eat that for 2–3 weeks while tracking weight, then adjust by ±200 kcal/day based on actual outcomes. The number on this page is a hypothesis; your scale is the experiment.
Related calculators
TDEE pairs naturally with several other Microapp tools depending on what you're tracking:
- For body mass index (a quick weight-status snapshot, separate from calorie targets), use the BMI Calculator.
- If you want to back into your TDEE from a desired calorie target — e.g. "what TDEE supports a 1,800 kcal cut?" — the Calorie Calculator handles the reverse direction.
- For body-fat percentage estimation using the Army's tape-measure method (no scale needed), use the Army Body Fat Calculator. The result feeds into Katch-McArdle when that becomes available.
- To convert weight between kg and lb (or any other unit) for entering your number, the Weight Converter handles all common units.
Frequently asked questions
Which formula is the most accurate — Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle?
For most adults, Mifflin-St Jeor. The American Dietetic Association's 2005 review found it predicts resting metabolic rate within 10% of measured values for the majority of healthy non-obese adults — better than Harris-Benedict, which dates from 1919 and tends to overestimate. Katch-McArdle can be more accurate when you know your body-fat percentage, since it calculates from lean body mass rather than total weight — useful for very lean or very heavy people. The TDEE Calculator uses Mifflin-St Jeor by default.
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories you'd burn if you spent the entire day lying motionless in a thermoneutral room — just keeping your organs running, your blood circulating, your body warm. TDEE adds everything else: walking, working, exercising, fidgeting, even digesting food (the "thermic effect of food" is about 10% of intake). For a sedentary person, TDEE is roughly 1.2× BMR; for very active people, it can be 1.9× BMR.
How fast can I lose weight using my TDEE?
The cut target shown (TDEE − 500 kcal/day) produces about 1 lb (0.5 kg) per week of fat loss for most people. That's the sustainable maximum for body-recomposition without significant muscle loss. Steeper deficits (>750 kcal/day) work for short-term aggressive cuts but increase muscle loss, hunger, and rebound risk. Athletes and very lean people often use smaller deficits (250 kcal/day) to preserve performance.
Why do my TDEE estimates from different calculators vary so much?
They're using different formulas, different activity-multiplier definitions, or different assumptions about lean mass. A 100–200 kcal/day variance between calculators is normal. The right number isn't found in the calculator — it's found by eating at the calculated number for 2–3 weeks and watching your weight. Adjust by ±200 kcal/day based on what actually happens.
Should I include my exercise calories on top of TDEE?
No — the activity multiplier already includes typical exercise for your activity level (e.g. Moderately Active assumes moderate exercise 3–5 days/week). If you also log gym sessions and add those calories on top, you'll double-count by 30–50%. Pick the activity level that reflects your average week including exercise; don't add exercise as a separate budget.
Does TDEE account for muscle mass?
The Mifflin-St Jeor formula uses total weight, which correlates loosely with lean mass but doesn't measure it directly. Two people with the same weight but different body-fat percentage will have slightly different actual TDEEs (the leaner one burns more). For more accurate calculations when you know your body-fat percentage, the Katch-McArdle formula uses lean mass directly — that's a v2 feature on this calculator. Until then, Mifflin-St Jeor is accurate within about ±10% for most adults.
Why does my TDEE drop when I lose weight?
Two reasons. First, the formula is weight-based — 80 kg burns more than 70 kg at rest, so when you weigh less, your BMR is mathematically lower. Second, your body adapts to sustained calorie deficits by lowering metabolism slightly (called "adaptive thermogenesis," typically 5–15%). After every 5–10 lb (2–5 kg) of weight loss, recalculate your TDEE at the new weight and adjust your intake.
Is the calculator stored or sent anywhere?
No. The calculation runs entirely in your browser using JavaScript — nothing is sent to a server, logged, or stored. Once you close the tab, your inputs are gone. The same applies to every Microapp tool.