Puppy Collar Size Guide. The chart will tell you the sizes of the top piece and front piece which usually goes with that particular size of girth piece. The collar should be small in size but large enough to cover the neck of the puppy.

Chihuahua, toy poodle, jack russell. Choose an appropriate collar width for your puppy. Based on that formula, a border collie puppy that weighs 8 lbs at 13 weeks would likely weigh 32 lbs as an adult.
You need to order a collar depending on your dog’s specific neck and head size to buy the correct collar right off the bat.
A lightweight and small collar would work best for a puppy. A collar is measured from the end of the leather near the buckle to the middle hole; You need to order a collar depending on your dog’s specific neck and head size to buy the correct collar right off the bat. If your dog has a 18 1/2″ neck then it gets a 18″ collar