Help with staffy adult MALE collar size please?

Question in title guys, I'VE WON   a like & share competition on Facebook & won a handmade leather staffy collar!    I need to order it but my problem is Bo is only 4 & half months old so I just wondered if any of you with adult males know what collar size they are so I know which one to order, I know they all vary but there will hopefully be an average size! The person who makes them said generally it's around 22"?...

22 would be a bit on the large size for Douglas - who is fairly chunky, at 21.6 kilos. I recently had a coat made for him and measured his neck at 16-18 inches.

Bitches are generally smaller. But Darcy is 17 months and her collar is around 15"

ah maybe that size was with the added 4" that they add on for extra? He's not a big leggy staffy, he's chunky but small overall if that makes sense! His mum was the tiniest staffy I've ever seen & dad is quite a short but very chunky boy....hmmm may just have to be a guestimate!

Not much help as I have a little girl who wears pretty floral collars!!   But probably best to go slightly bigger than under estimate as you can always get an extra hole punched in it   

I would say 20" but as said previously it might be wise to have a little
spare just in case   

I would go with Sazzle Get it slightly bigger and then if need be you could trim the end and punch another hole!

Just for reference Rocky has a neck size of 42 cm or 16.5 inches and he is now fully grown, however is a cross so is not going to be a standard size.