When measuring your dog for a Snap-Around Training Collar, place your dog in a standing position. Measure under the chin, around the neck, and then up behind the ears. You want a Snug fit, but not choking.  Add an extra ½" for smooth coated dogs, or 1" for long coated dogs to the measurement obtained. This ½" - 1" will give the necessary check with less effort, and will help the collar stay in place. 

If you are ordering a Snap-Around Training Collar for a puppy (not an Adjustable Snap-Around), add 2" larger to allow for growth. When you get the collar, tie a knot, maybe two knots in the center of the collar to take up slack. This will make the collar smaller, and you can get the proper fit you need now while training your puppy. As the puppy grows, let the knot or knots back out to make the collar larger. This will also prevent you from having to purchase several collars while that puppy grows.