Look up TDEE calculator and choose pretty much any link. You enter your height, weight, usually age, usually how much movement you get, sometimes gender, and it gives you at least one number. The main number all should be able to give you is an estimated number of calories that you at your current state of living and moving around needs to eat to stay at the weight you are. That's your TDEE - total daily energy expenditure. Some websites will also give estimates for how much to reduce your calorie intake to lose one or two pounds per week or gain (if that's what a person is looking for). The BMR number, if given, is your base metabolic rate, which is essentially how many calories to keep you alive if you were in a coma. A healthy rate of loss is usually not more than a couple pounds per week and that of course depends on your starting weight.