With a tape measure, measure around your dogs nose as in the picture below. Placing a finger under to ensure enough space for your dog to be comfortable.

Note:- The muzzle should not be tight - it's better to be a little loose than too tight!
Recommended for the following breeds:-
X Small
(measurement around the dogs nose 10cm)
Yorkshire Terrier, Chihuahua,Miniature Poodles, Dwarf Dachshund.
Small
(measurement around the dogs nose 12cm)
Whippet, Jack Russel Terrier, Dachshunds, Miniature Poodle.
Medium
(measurement around the dogs nose 15cm)
Miniature Schnauzer, Border Collie, Springer and Cocker Spaniel, Poodle.
Large
(measurement around the dogs nose 19cm)
Medium-sized Schnauzer, Retriever (female), Doberman (female), Labrador, Boxer, Staffordshire Terrier.
Large Short
(measurement around the dogs nose 24cm)
Schnauzer, Retriever (male), Doberman (male), Rottweiler (male).
X Large
(measurement around the dogs nose 21cm)
Rottweiler (male), Leonberger, Great Dane.
