The amount of calories that you should eat every day depends very much on your body, but the most important thing is that you eat the same amount that you burn.
To find out how many calories you burn regular you can use the online calorie calculator . If you want to lose weight, you should eat less than you burn every day. The difference should be about 1000 calories, this if you want to lose about 2 pounds a week. If the weight loss is not so urgent i suggest you to keep the difference at about 500 calories.
The amount is not the only thing important when you want to lose weight. You should divide the calories in 3-5 meals. Do not eat the whole amount at a time and then hunger yourself. This is a bad habit and you probably won't lose weight at all.