Calorie Calculator
Estimate how many calories you need per day based on age, weight, height, and activity.
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Result
The formula
Mifflin-St Jeor is considered the most accurate BMR formula for most adults. Multiply BMR by activity factor for TDEE.
Worked example
- Male, 30 yrs, 75 kg, 178 cm, moderate activity
- BMR ≈ 1,738 kcal
- TDEE ≈ 2,694 kcal
Result: 2,694 kcal/day
How calorie needs are estimated
No equation knows your exact metabolism. These formulas approximate resting burn, then scale for activity.
Mifflin–St Jeor BMR
Published in 1990 and often more accurate than older Harris–Benedict equations for modern adults. It predicts resting energy — not athletic performance.
Sex-specific constants reflect average differences in body composition; they are population averages, not a judgment about any individual.
Activity multipliers (TDEE)
Common factors run from about 1.2 (sedentary) to 1.9 (very high activity). They are broad buckets. Someone who sits all day but trains hard three evenings may sit between “light” and “moderate.”
Weight goals
A rough rule of thumb is that about 500 kcal/day below TDEE supports gradual weight loss and 500 above supports gain — but adaptation, NEAT, fluid shifts, and adherence matter more than spreadsheet precision. Illness and medication change needs; seek medical advice when relevant.
Food-label limits
Package calories use Atwater factors and rounding. Lab measurements can differ. Daily tracking is approximate by design.
Interesting facts
Mifflin-St Jeor
Published in 1990, this formula is generally more accurate than Harris-Benedict for contemporary adult populations.
BMR is not your daily budget
Basal metabolic rate is the energy you would burn at complete rest. Most people need TDEE — BMR multiplied by an activity factor — for meal planning.
Activity factors are estimates
Sedentary (~1.2) through extra-active (~1.9) categories are coarse. Wearables and training logs help refine, but they still have error.
A pound is not exactly 3,500 kcal
The old “3,500 kcal = 1 lb” rule oversimplifies. Water, glycogen, and metabolic adaptation mean real-world weight change is messier than a fixed calorie gap.
Frequently asked questions
Total Daily Energy Expenditure — calories burned including activity. Eating below TDEE tends to support weight loss; eating above tends to support gain.
Usually not. BMR assumes rest only. A moderate deficit from TDEE is more sustainable and safer for most adults than eating at or below BMR.
Formulas use averages. Trackers use heart-rate models and assumptions about your fitness. Treat both as ranges and adjust based on how your weight and energy actually change over weeks.
Many people lower intake slightly on true rest days, but large day-to-day swings are optional. Weekly averages matter more than perfect daily matching.
References
- Dietary Guidelines for Americans Energy needs vary by age, sex, size, and activity.
- Human energy requirements Scientific basis for estimating energy expenditure.