Here's a website with a Daily Energy Expended calculator:
http://www.healthstatus.com/calculate/dee
Select your gender, your age, height and weight and it will tell you how many calories your body burns each day to keep you at the weight you are at.
To stay at the weight you are currently at, eat approximately that amount of calories. To lose weight, eat fewer calories than the amount shown. To lose a pound, you need to burn at least 3500 calories more than you've eaten.
For example, if your body burns 2000 calories per day to keep your body functioning, multiply that number by 7 (seven days in a week) to get 14,000. Now subtract 3500 (for one pound) from that number to get a weekly calorie intake of 10,500. Divide that number by 7 (days of the week) to find out your daily caloric intake of 1500 calories to lose one pound a week.
Kimberly