About the Calorie Needs Calculator
This estimates how many calories you need per day — your Total Daily Energy Expenditure (TDEE) — to maintain your current weight, and rough targets for losing or gaining weight. It builds on your Basal Metabolic Rate and adjusts for how active you are. It's the practical starting point for planning a diet, a fat-loss phase, or a muscle-gain bulk.
How it works
First it calculates your BMR with the Mifflin-St Jeor equation (calories burned at rest). Then it multiplies by an activity factor to get your maintenance calories (TDEE):
- Sedentary ×1.2, Light ×1.375, Moderate ×1.55, Active ×1.725, Very active ×1.9.
For weight change it uses the common rule that roughly 7,700 calories ≈ 1 kg of body weight, so a 500-calorie daily deficit loses about 0.5 kg per week, and a 500-calorie surplus gains about the same.
Assumptions and behaviour
- BMR uses Mifflin-St Jeor; the activity multipliers are the standard TDEE factors.
- The lose/gain figures use a ±500 kcal/day adjustment for about ±0.5 kg (about 1 lb) per week.
- Pick the activity level that honestly matches a typical week — most people overestimate it.
- Results are rounded to whole calories.
Limitations
- These are population-average estimates. Real energy needs vary with body composition, genetics, hormones and non-exercise movement, so treat the numbers as a starting point and adjust based on how your weight actually responds over a few weeks.
- The 7,700 kcal-per-kg rule is a simplification — real weight change isn't perfectly linear, and very aggressive deficits are counterproductive and unsafe.
- Activity multipliers are broad brackets, and the biggest source of error is misjudging your activity level.
- This is general information, not medical or dietary advice — talk to a doctor or dietitian before a significant change, especially with health conditions.
Privacy
The calculation runs entirely in your browser. Your details are never uploaded or stored.
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