On longbows, what do you consider the throat circumference on a small, medium, and large grip?  I was thinking 4 3/4, 5, and 5 1/4".  What do you think?

That sounds pretty good maybe plus or minus a 1/8",from bows I've replaced the leather grip on and measured them.The largest grip on one of my Hill's was 5&1/8" but I got them used.On my Hill blank I made it right at 5" with a very mild locator.

Anyone else?

Agree with  JRY309, prefer them about 5 in.

I was thinking the same thing about some kind of standard sizing I could apply to grips. I tend to prefer a small grip for my clubby hands. Alot of the guys I show some bows to tend to prefer a little larger grip it seems.

Bear Kodiac Magnum-5"
Treadway          -4 3/4"
Black hawk        -5"
Z bow (custom)    -5 3/8"
Homemade          -4 7/8"
Homemade          -4 3/4"
Homemade          -5 1/4"
Homeade           -5 3/8"

Just measured these after you peeked my interest Marty. Wow! I never measured my grips before, looks like I like'em in the 5" inch range. My Treadway has a sleave that rolls on over the grip, Im guessing it will be close to the five inch mark as well.
When I got my Z bow made, Zach had me put my left hand on a sheet of paper palm down with my index finger and thumb making a "L" 90 degree angle to fit the grip size. Its the most comfortable of all my bows to hold, but I still cant shoot it as well as the Treadway!!

Anyone else with grip measurements to help make a larger comparison would be cool!

Got 4 youth bows all have 4" grips.

My recurves are 5 1/4" at the throat.  I think I have average sized hands and they fit my hand real good. This measurement was taken off of 2 Blacktail TD Elites.

My Wes Wallace long bow is 4 7/8"
My G & L longbow is 4 7/8" also