If you want to calculate exactly how many calories you need to lose weight, TDEE is a great place to start. TDEE (Total Daily Energy Expenditure) shows how many calories you burn in a day, taking into account all activities. In order to start losing weight, you need to consume fewer calories than your TDEE. It is usually recommended to create a deficit of 10-20%. So if your TDEE is 2500 calories, then to lose weight you need to eat 2000-2250 calories per day. Personally, I use the tdee calculator. You can enter your age, weight, height, and activity level, and it will give you the result you need right away. This calculator is very convenient and easy to use.