What yardage am I losing with 13 degree driver?

I have no idea how long I actually hit it but if I hit it say 200 yeards, how much further would I expect the ball to go if I used the same club but with 10.5 degrees & hit it exactly the same?

It would go shorter. I'm 100% convinced. Not every ball, because you'll get lots of roll with a 10 degree driver, but the carry will be way down for your needs.

If you hit it say 240, then we'd have a competition.

If you hit it 275+, then we could be into serious distance loss territory.

Nobody believes me, but I don't care.