B.B. Simon Size Guide
 
 
Dog Collars

Size
Adjustable Length
XSmall 6 1/2" to 9 1/4"
Small 8 1/2" to 11 1/2"
Medium 10" to 13"
Large 12 1/2" to 15 1/2"
XLarge 14 1/2" to 17 1/2"

 
 
Measure the exact (comfortable) measurement of your dog's neck where the collar will sit using a seamstress cloth tape or a piece of string. This will be slightly loose and not tight. 
 
 
If you are not sure, please call us at 877-800-8181 to speak to a customer service representative.