Sure - go to
http://www.bmi-calculator.net/bmr-calculator/ and figure out what your BMR is.
Depending on what that number is, you want to drop the calories no more than 1,000 per day.
For instance, my number is 2526.64 -- that's the number of calories based on my current age and weight and activity level I need per day to maintain my current weight.
If I want to lose a pound a week, I drop that number by 500. If I want to lose 2 lbs a week, I drop that number by 1000. So I should eat 1526.64 calories a day to lose 2 lbs a week -- on average.
The kicker is that if you do a lot of exercise and burn a lot of calories, you have to add those calories back into your total. For example, if I eat 1526.64 calories today, but I burn off 500 of them exercising, then I only really ate 1026.64 -- which isn't enough for the amount I weigh right now.
So, I would actually eat my 1526.64 calories plus the 500 I burned off for exercise in order to balance out at the 1526.64 net I need for the day.
It's working for me, and if you are not losing weight and you are heavier, you may not be taking in enough calories and putting yourself into starvation mode.