Quick answer: A moderately active 30-year-old man of 70 kg and 170 cm maintains his weight on about 2,507 kcal a day; to lose 0.5 kg a week he would eat about 2,507 − 550 = 1,957 kcal.
How it's calculated
First the calculator finds your basal metabolic rate with the Mifflin–St Jeor equation (10 × kg + 6.25 × cm − 5 × age, + 5 for men or − 161 for women), then multiplies it by an activity factor from 1.2 to 1.9 to get your maintenance calories (TDEE).
For a goal it adds or subtracts calories using the common estimate that 1 kg of body weight holds about 7,700 kcal: 0.5 kg a week is 7,700 × 0.5 ÷ 7 = 550 kcal a day. Some calculators use a round 500 kcal a day for 0.5 kg (1,000 for 1 kg), so their targets come out about 50–100 kcal higher.
The 7,700 kcal rule is a simplification: as you lose weight your energy needs fall too, so progress slows unless you recalculate. The result also cannot account for muscle mass, medical conditions or medicines that change metabolism. Use it as a start and adjust by your real weight trend over a few weeks. To split the calories into protein, carbs and fat, use the macro calculator.
Worked examples
- Man, 30, 70 kg, 170 cm, moderate, lose 0.5 kg/week: 2,507 − 550 = 1,957 kcal
- Same man, maintain: 1,617.5 × 1.55 = 2,507 kcal
- Same man, gain 0.25 kg/week: 2,507 + 275 = 2,782 kcal
Frequently asked questions
How many calories should I eat to lose weight?
About 550 kcal a day below your maintenance level for roughly 0.5 kg a week. The table above shows each goal for your numbers.
How fast is it reasonable to lose weight?
Public health guidance such as the NHS and CDC generally describes 0.5 to 1 kg a week as a steady rate for adults.
Why has my weight loss slowed?
A lighter body uses less energy, and water and glycogen changes hide fat loss at first. Recalculate with your new weight.
Do I count the calories I burn in workouts?
No, not on top. The activity level already includes your usual exercise.
How many calories are in 1 kg of body fat?
About 7,700 kcal, which is why losing 0.5 kg a week needs a deficit of about 550 kcal a day. Real results vary, because your body adapts as you lose weight.
When should I recalculate?
After every few kilograms or when your activity changes. A lighter body uses less energy, so the same intake gradually becomes a smaller deficit.