A. Measure length of pet's back from the base of the neck to the base of the tail.
B. Measure neck circumference.
C. Measure the broadest part of the chest.

If the measurement is between sizes, we recommend going up one size. Also, if pet has a stout build, a deep chest, or is overweight, we recommend going up a minimum of one size for proper fit. If the dog is long-backed, like a Dachshund, a smaller size is recommended.