Asking this question on the net, not many according to several search engines.

Perhaps 100 for an actual orgasm; although you also have to count the amount of effort spent building up to the climax, plus what is burned during the refractory/recovery period that follows an ejaculation. There is no one answer, only a range because of how much effort and time a person puts into each individual act. Perhaps another 50-100 calories.

-doc