• X-Small - neck sizes 8 - 11 inches
• Small - neck sizes 12 - 15 inches
• Medium - neck sizes 16 - 19 inches
• Large - neck sizes 20 - 23 inches
• Extra Large -  neck sizes 24 - 27 inches

Measuring your dog's neck
We recommend using a soft measuring tape. If you don't have one - use a piece of string, and measure that. Remember - you'll want to get two fingers under the collar when it's on, so take that into account.