Susan, I start out with size 3 for bantam and size 4 for LF. It doesn't take long for them to graduate to the next size up. Years ago I tried the larger sizes in the rubber stretch bands but found the chicks could remove them easily, especially when they went in outdoor runs. So after changing to the next larger size after hatching, the next time I start using the hard spiral plastic bands. I do occasionally lose a band with these but not to the extent on the larger rubber stretch bands. So if this makes sense I go for bantam 3,4,rubber stretch bands 5,6,7 hard spiral bands. LF 4,5 rubber stretch bands 6,7,9,10,11 hard spiral bands then 12,14 numbered plastic bands.