Measuring Method #1:
Simply measure your dog's neck at the base with a measuring tape or string. Allow room to slip two fingers between the measuring tape or string and your dog’s neck comfortably for the proper collar size.
Measuring Method #2:
You can also use your dog's current collar measurement if it fits correctly. Just unbuckle the collar, lay it out flat and measure from the adjustment hole being used to the center of the buckle. We have found that this is usually the most reliable measurement to use.