19 gauge is very then & while it will hold the birds just fine it is easily damage by you handling it. I'd suggest 1/2x1 for the bottom & 1x1 for the top & sides unless you are concerned about predators that you need the smaller wires on the sides also. This is also assuming your talking about Coturnix.
I've used the 1/4" hardware cloth but it is more work to clean on top of not as sturdy. Bitties need something in the bottom not to fall through tho.
Thanks for the reply yes I was talking about courtnix and a&ms I'm probably going to go with 1/2x1 for the bottom and 1" on the top and sides like u said