Measure around the dog's neck with an allowance for 2 fingers to fit between the dog and the collar. The collar shouldn't be so tight that it will cause discomfort or so loose that it slides over the dogs head.
Sizes Fit Range
14”: 11” to 14”
16”: 13” to 16”
18”: 14” to 18”
20”: 16” to 20”
22”: 18” to 22”
24”: 20” to 24”
26”: 22” to 26”