How daily calorie needs are estimated
First the calculator finds your BMR (resting calorie burn) with the Mifflin-St Jeor equation, then multiplies it by an activity factor to get your maintenance calories (TDEE). Goal targets simply add or subtract a calorie adjustment from that maintenance figure.
Using the goal targets
- Lose weight — eat below maintenance (a moderate deficit).
- Maintain — eat at maintenance.
- Gain weight — eat above maintenance (a moderate surplus).
Frequently asked questions
How many calories do I need per day?
Your maintenance calories equal your BMR multiplied by an activity factor. Eat around that number to maintain weight, fewer to lose, and more to gain.
How big should a calorie deficit be?
A deficit of about 500 calories a day is a common, sustainable target for roughly half a kilogram (about one pound) of weight loss per week. Very aggressive deficits are harder to maintain and may not be healthy.
Are these numbers exact?
They are well-validated estimates. Real needs vary with body composition, genetics and daily movement, so adjust based on how your weight actually changes over a few weeks.
Should I eat below my BMR?
Generally it is not recommended to eat below your BMR for long periods. For personalised guidance, especially with health conditions, consult a doctor or dietitian.
For general information only — not medical advice.