It is important to measure your dog as accurately as possible to determine a proper fit.  With a measuring tape and your dog in a standing position, use the chart to to fit your dog for collars, harnesses and apparel. 

A dog's garment size is determined by
measuring from the base of the neck to the base of the tail.

A  Measure your dog's LENGTH from the base of its neck to the base of its tail.
B  Measure around the NECK, close to the shoulders.
C Lastly, measure around the CHEST just behind the front legs.