Your Estimated BMR (calculated at http://phord.com/cc):
BMR=1396 :: RMR=1675

Your customized recommendation:
EAT 1396 calories :: BURN 2010 calories :: LOSE 1.23 lb per week

Reasoning:

Deficits: Your deficit is the difference between how many calories you eat and how many calories you burn. Your recommended deficit is 614 calories. This is the least of your Activity Deficit (614 calories), your Safety Deficit (864 calories), and your Maximum Fat Calorie Expenditure (2010 calories).

Activity Deficit (614 calories): This is the number of calories you burn in your daily activities (such as being awake, driving to work, exercising, doing homework, etc.). This is an estimate based on the amount of exercise you indicated you do each week in the form above, averaged out for daily deficit numbers. For sedentary individuals this is 20% of your BMR.

Safety Deficit (864 calories): Nutritionists say that you can safely lose no more than 1% of your body weight per week. For the weight you gave (172.8 lb), you can safely lose about 1.73 lb per week. Because each pound of body fat contains 3500 calories of energy, your safe deficit is 1.73 lb * 3500 calories per pound per week = 6048 calories per week, which comes to 6048 / 7 = 864 calories per day.

Maximum Fat Calorie Expenditure (2010 calories): One study found that body fat in humans can be converted to energy at a maximum rate of 31 calories per pound of actual body fat per day. Any energy you expend beyond this rate comes from your intake of nutrients and the breakdown (catabolysis) of your muscles. Weight loss in most people consists of about 75% FAT and 25% MUSCLE. Since we can calculate the actual amount of body fat in your body using your Body Fat Percentage (if given), we can determine the optimal calorie deficit to focus on FAT BURN instead of MUSCLE LOSS. To optimize your FAT BURN instead of MUSCLE LOSS, you should choose a deficit that does not exceed this value. (Persons wishing to lose muscle as well as fat can ignore this deficit limit.)