Because dogs come in all sizes, the leads do too.The measurement needs to go from where the lead attaches to your Working Wonders Belt to where it attaches comfortably to the dog. The larger the dog, the shorter the lead.
 
All leads have a measure of adjustability, they come in the following approximate sizes:
 
Long:19 - 30 inches
Medium: 14 - 20 inches
Short: 11 - 14 inches
Extra Short: 10 - 12 inches

Working Wonders Belts and Short leads are sold separately