What angle do I cut?

Are you just cutting the trim boards that face the window or what?

This might help. There are too many wooden parts to a window, each with different angles. It can also depend on how out of square your window is.

For the facing boards of trim, know that each corner is a 90 degree angle. If your windows are square, then each board coming into the angle is half that (45 degree angle), but for some windows, you will have to tweak this a bit.

not enough info to say

Sorry it was trim that I am trying to cut for around the window. I didn’t think it was 45 for some reason.

It depends on the style.I often see 45 degree angles on inside trim.My house has Craftsman style window trim which is at 90 degrees.

It was 45 and I didn’t want to waste wood thank you, thank you.