How many calories do I need every day if I want to lose 2 pounds a week?

I also work out about 3 times a week doing cles at the gym (yoga and a cycle cl) and swimming laps for about 40 minutes to an hour at the pool. I may bump up my workout regimen to 4 days a week eventually. I'm only trying to lose about 10 to 15 pounds. My weight right now is probably at around 145. I'm also a vegetarian but I do eat fish. Any suggestions for healthy weight loss would be great. Thanks!