Calorie calculator
This free calorie and TDEE calculator finds your daily calorie needs to maintain, lose or gain weight — based on the Mifflin-St Jeor equation used by dietitians.
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How your calorie needs are calculated
This tool first calculates your BMR (Basal Metabolic Rate) using the Mifflin-St Jeor equation — the formula recommended by the American Academy of Nutrition and Dietetics. Your BMR is then multiplied by an activity factor to estimate your TDEE (Total Daily Energy Expenditure). The donut above shows the split: BMR is the energy you'd burn lying still all day, and "activity" is everything on top of that from movement and exercise.
- Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
- Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
Worked example: 30-year-old male, 170cm, 70kg
BMR = 10×70 + 6.25×170 − 5×30 + 5 = 700 + 1,062.5 − 150 + 5 = 1,618 calories (energy burned at complete rest).
Multiplying BMR by the activity factor gives TDEE (maintenance calories) at each activity level:
| Activity level | TDEE (maintain) | Lose ~0.5kg/wk | Gain ~0.5kg/wk |
|---|---|---|---|
| Sedentary (little/no exercise) | 1,941 | 1,441 | 2,441 |
| Lightly active (1–3 days/wk) | 2,224 | 1,724 | 2,724 |
| Moderately active (3–5 days/wk) | 2,507 | 2,007 | 3,007 |
| Very active (6–7 days/wk) | 2,790 | 2,290 | 3,290 |
| Extra active (physical job + training) | 3,073 | 2,573 | 3,573 |
Notice how much activity level alone shifts the target — the same person's maintenance calories swing by over 1,100 calories/day between sedentary and extra active, which is why picking an honest activity level matters more than the BMR formula itself.
Calorie deficit vs surplus
Eating below your TDEE creates a calorie deficit, which leads to weight loss over time; eating above it creates a surplus, which leads to weight gain. A deficit or surplus of about 500 calories a day roughly corresponds to 0.5 kg (about 1 lb) of change per week, since a kilogram of body fat stores roughly 7,700 calories. Very large deficits are harder to sustain and can affect energy levels, so a moderate, steady approach usually works better long-term.
Looking to combine this with a target weight? Check your BMI and see our guide on how many calories to lose weight.
What this calculator does not include
- Body composition — the Mifflin-St Jeor equation uses weight, height, age and sex only. It doesn't account for muscle mass, so a very muscular person's real calorie needs may run higher than this estimate.
- Macronutrient split — this gives a total calorie target only; use our macro calculator to split that number into protein, carbs and fat.
- Medical conditions — thyroid conditions, certain medications and metabolic conditions can shift real energy needs away from the formula estimate.
Treat the TDEE number as a starting point, not a fixed target. Weigh yourself weekly (not daily — day-to-day fluctuation from water and food is normal) and adjust your intake by 100–200 calories if your weight isn't trending the way your goal expects after two to three weeks.
Frequently asked questions
How many calories should I eat per day?
Most adults need 1,600–3,000 calories depending on age, sex, size and activity. Use your TDEE above as the starting point.
How many calories to lose 1 lb a week?
Roughly a 500-calorie daily deficit — one pound of fat stores about 3,500 calories.
What is TDEE?
Total Daily Energy Expenditure — all calories you burn in a day including activity. Eat at TDEE to maintain, below to lose, above to gain.
What's the difference between BMR and TDEE?
BMR is calories burned at complete rest; TDEE adds your activity level on top — TDEE is always the higher, more useful number for daily planning.
Is this a TDEE calculator too?
Yes — the main result above is your TDEE (Total Daily Energy Expenditure), calculated from your BMR and activity level. Use it directly as your maintenance calorie target, or subtract/add ~500 for weight loss or gain.
How do I pick the right activity level?
Be honest, not aspirational. "Moderately active" means structured exercise 3–5 days a week on top of a normal daily routine — a desk job with two gym sessions a week is closer to "lightly active." Overestimating activity level is the most common reason people don't lose weight despite "eating at a deficit."
This tool is for information only and is not medical advice.