The honest answer: eat a few hundred below your maintenance calories (TDEE), and never below your BMR. Enter your details and the calculator gives you a safe daily target.
Weight loss comes from a calorie deficit — eating less than you burn. There are roughly 7,700 kcal in a kilogram of body fat (about 3,500 per pound), so a daily deficit of 500 kcal targets around half a kilo of loss per week. That's the figure in the LOSE box above.
Because aggressive deficits backfire. Eating at or below your BMR tends to cost you muscle, tank your energy, and become impossible to sustain. A moderate deficit you can actually keep is what produces results. This calculator caps the weight-loss target at your BMR for exactly this reason.
Here's what most "how many calories" answers leave out: as you get lighter, you burn less, so the deficit shrinks and progress stalls on a fixed target. The planner recalculates your target every week so the deficit holds all the way to your goal.
Roughly 500 kcal/day below your TDEE (maintenance). The calculator's LOSE figure uses this default and shows your personalised number.
For many adults, 1,200 is below BMR and too low to sustain safely. This calculator won't set a target below your BMR. If your math points that low, lose more slowly or consult a professional.
Calories drive weight change; macros (especially adequate protein) help you keep muscle while losing. The macro split above is a reasonable starting point.