A pound of body fat (see image) equates to approximately 3500 calories. So a calorie deficit of 500 calories (meaning that you burn 500 calories more than you eat each day) you would lose approximately one pound per week:
500 x 7 = 3,500
A calorie deficit of 1000 calories would mean that you'd lose approximately two pounds per week. That's a good number to remember, because two pounds a week is commonly accepted as the maximum rate of weight loss that is healthy.
Here are some exercise-related calorie calculators to experiment with: