here is a BMR calc


http://www.room42.com/nutrition/basal.shtml

remember this just gives you a general idea of the minimum amount of calories your body had to burn daily to stay alive. The result you get is supposedly how many calories you would burn daily just for basic metabolism. Everyone is not the same so my suggestion is to view your BMR as guideline for caloric intake. If you stay at or slightly below your BMR, you should lose weight. Some people can go way above their BMR and lose weight if they are active, others cant.

hope this helps