I need (approximate) average size man sweater back size

Help please!! I am knitting a sweater for my son. Because of covid I’m doing this blind. When I asked him his measurement from underarm to where he wanted the waist to sit, he told me 19" (which I thought was too long). I’m almost done with the back; I think the sweater will easily fit a giraffe. Can anyone give me an average man’s length underarm to waist? I hate to rip it out but I think I’m making a sweater for Wilt Chamberlain!

What a wonderful project! Nineteen inches does sound long. Maybe your son was measuring underarm to bottom of sweater?
Here’s a chart that may help:

Thanks for your help. I asked him to give me the measurements of a favorite sweater. I am now sadly in the process of ripping out. It was definitely too big. :worried:

So painful but somehow, reknitting seems to go faster. Good luck with it!