Here's the easy answer for you: (Thanks to Musceandstrength.com)
Basal Metabolic Rate and Daily Calorie Calculator | Muscle&Strength.com
You can use this to work out approximately what your body needs in terms of calories. Then subtract 500 per day for weight loss. You may need to take off more or less, you just need to test for yourself really.
Remember that's it's just as important where your calories are coming from as how many you're getting!