simulation button/program

[dogscoff]

There are all sorts of possible reasons. Maybe the fleets strategies/ formations were different in the real battle. Maybe some of the enemy ships started the real battle damages or low on supplies.

The simulator is usually pretty good, as long as you don't get too complicated with it. When you start adding planets, bases, units etc it can get a little wierd. For normal ship - ship combat it ought to give you fairly good results.