If it gives you any better idea of their size, most all of my breeders are in 'cages' made out of a cubby shelf. Each cubby is 11" by 11". They have plenty of room. Baby buttons can get through 1/2" wire, they don't even have to struggle, just waltz right through.
Button 'cages':
3-day old button chick next to a 1-day old coturnix chick:
4-day old Button baby heading into their hidey hut (intended for use in hamsters or mice)
In my grasp at 1-week old:
Button eggs on 1/4" wire:
Buttons in a fish tank (10-gal. tank with 12 buttons):
I think this one probably shows the size of a serama better than a button, they are pretty small
3-week old serama with 5-week old button (black chick on left is a LF, about 1 week old):
Oh, this might help. Serama chicks next to a silkie bantam chick (white) and a LF chick (brown in center of pile). The serama are 3 weeks old, the silkie and LF are about 1 week.
I'm sure I have more pics, but I think that's enough for now