Calorie Deficit Calculator — Free
Your calorie deficit targets
This free Calorie Deficit Calculator starts from the only number that matters for weight loss — your maintenance calories — and turns it into a daily eating target. It first estimates your BMR and TDEE with the Mifflin-St Jeor equation, the formula studies generally find most accurate, then subtracts a deficit at three sensible paces: a mild 250-calorie deficit for about a quarter kilo a week, the standard 500-calorie deficit for about half a kilo a week, and a larger 750-calorie deficit for those with more to lose. Your deficit targets are highlighted first, because "how much should I eat to lose weight?" is the question this page exists to answer.
A calorie deficit simply means eating less energy than you burn, and the size of the gap sets the speed: one kilogram of body fat stores roughly 7,700 calories, so a steady 500-calorie daily gap adds up to about half a kilogram a week. Bigger is not automatically better — very large deficits are hard to sustain and risk muscle loss and fatigue, and targets below about 1,500 calories a day for men or 1,200 for women are flagged here, because going lower belongs under medical guidance. Treat every figure as an estimate, not medical advice: track your real weight trend for two or three weeks and adjust the target by what actually happens. Everything runs locally in your browser; your details are never uploaded or stored.
How to use
- Select your sex and enter your age in years.
- Enter your current weight in kilograms and height in centimetres.
- Choose the activity level that honestly matches a typical week.
- Click Calculate my deficit to see your maintenance calories and three deficit targets.
- Start with the standard deficit, track your weight for two or three weeks, and adjust.
Frequently asked questions
What calorie deficit do I need to lose 0.5 kg a week?
About 500 calories a day below your maintenance. Half a kilo of body fat is roughly 3,850 stored calories, and 500 × 7 days = 3,500 — close enough that the standard deficit is the classic recommendation. This calculator shows that target in the middle row, worked out from your own maintenance figure rather than a generic guess.
Is a 1,000-calorie deficit safe?
For most people it is too aggressive to start with: hunger, fatigue and muscle loss climb sharply, and for smaller or less active people it pushes intake below safe minimums. The calculator caps its suggested plans at a 750-calorie deficit and flags any target under 1,500 (men) or 1,200 (women) calories a day. If you think you need more, that is a conversation for a doctor or registered dietitian.
Why am I in a deficit but not losing weight?
Usually one of three things: the activity level chosen was optimistic, portions are larger than estimated (oils, sauces and drinks are the classic hidden calories), or the scale is masking fat loss with water retention for a week or two. Judge by the three-week trend, not single weigh-ins, and re-check your maintenance with honest inputs.
Should I eat back the calories I burn exercising?
Generally no, if your activity level was set honestly — exercise is already inside your TDEE. Eating back estimated workout calories on top usually erases the deficit, because fitness trackers tend to overstate exercise burn. Only add food back for genuinely exceptional days of heavy exertion.