For proper size, measure as shown

Picture
 
Collar Size

Extra Small (includes cats)

Small

Medium

Large

Extra Large
Width

3/8"

1/2"

3/4"

1"

1"
Fits Neck Size

7 to 11 inches

10 to 15 inches

12 to 19 inches

15 to 24 inches

17 to 29 inces