Welcome, ucmesk8 View All Carts - Order Status - Privacy Policy - Edit Account - Sign Out The general rule of thumb is that the blade size should be 1/4" smaller than the length of the boot from back to front. Some skaters prefer to size from the very tip of the boot to the back of the heel to maximize available blade length, and for fast growing children's feet it is possible to "cheat" a little if a blade still has some life but a larger boot size is needed.