29" Monitor size question

Can anyone tell me the diameter of the of the actual play field that you get on a 29" monitor, Its just I picked up a 29" cabinet today with no Monitor and the plastic bezel has about 26" diameter I just wanted to make sure that ok.
Cheers Paul

Both my computer monitor and two TV's all have a diameter 0.8 times that of the diagonal measurement of the screen.

I dunno if arcade monitors are the same way? Should be about 23 inches...