Stretching as far as I can, from my index to my pinkie finger is exactly 5 inches wide (on my right hand).I really struggled trying to get a clear low F note on the Aulos (all holes covered)

I also measured the distance from the bottom two holes to the 4th hole up (holes that pinkie to index fingers cover on right hand) and found that the Yamaha is exactly a ¼ of an inch shorter in length than the Aulos