Measuring tips: If you're unsure of your dog's neck and chest size, use a soft measuring tape and wrap it around your dog's neck or the widest part of their chest (for harnesses). Make it snug but be sure 2-3 fingers can fit in between the measuring tape and your pup. If you don't have a soft measuring tape, take a string and wrap it around your dog's neck and chest. Then measure the length of the string.