Calorie Calculator: Estimating Daily Energy Needs (TDEE)
Your daily calorie need depends on your size, age, sex, and how active you are. The calculator estimates this using established formulas, then lets you adjust for weight-loss or muscle-gain goals. Treat the number as a starting point — your real-world response is what actually counts.
Total Daily Energy Expenditure (TDEE) is the calories your body burns in a typical day. About 60–70% goes to keeping you alive (basal metabolic rate, BMR), 20–30% to physical activity, and ~10% to digesting food (the thermic effect of food).
The most common BMR formula today is Mifflin-St Jeor (1990), which improved on the older Harris-Benedict equation. The calculator multiplies BMR by an activity factor to get TDEE — a working estimate of the calories you actually burn each day.
Activity multipliers
| Level | Multiplier | Description |
|---|---|---|
| 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 |
Goals: deficit, maintenance, surplus
**Maintenance** = TDEE. Eat what you burn and weight stays roughly stable. **Deficit** = TDEE minus 300–500 kcal/day for steady fat loss (~0.5 kg/week). **Surplus** = TDEE plus 200–300 kcal/day for lean muscle gain.
Larger deficits cause faster scale loss but more muscle loss and worse adherence. Larger surpluses just add fat. Slow and steady wins both directions.
Common mistakes that distort your number
- •Overestimating activity level. Most desk-workers who exercise 3 times/week are 'lightly active,' not 'moderately.'
- •Treating the calculator number as exact. ±15% individual variation is normal.
- •Forgetting that TDEE drops as you lose weight (smaller body burns less).
- •Ignoring sleep, stress, and hydration — all measurably affect daily expenditure.
- •Using BMR instead of TDEE as a target — BMR is what you'd burn lying in bed all day.
Extended FAQ
How accurate are these formulas?
Mifflin-St Jeor is accurate within ±10% for most people. Athletes, very lean or very obese individuals, and the elderly are more variable. Use the number as a starting point and adjust based on real-world weight-change response over 2–4 weeks.
Should I eat back my exercise calories?
If your activity multiplier already accounts for your weekly exercise, no. If you used 'sedentary' and add exercise on top, eating some of those calories back makes sense.
Is this safe for pregnancy or medical conditions?
No general calculator is appropriate during pregnancy, breastfeeding, or with a chronic medical condition (diabetes, kidney disease, etc.). See a registered dietitian or doctor.
Are my inputs stored?
No — runs entirely in your browser.