This page has great illustrations for proper measuring. Hope it helps.
http://www.2houndsdesign.com/How-to-Measure-for-a-Martingale-Collar.html
not sure if anone already knows about this site. i have purchased several collars from him.
http://members.aol.com/k9collars
john
These are nice! i like the safety choke design. I am going to order one. Thanks for posting.
Nick is very nice , he does this in his spare time , so if there is a delay in communication he is probably out on his hog . and will get back to you .
the collars are excellent quality.