Well, he is a rescue and was only 3 months at the time he was listed as a shepherd/hound. His weight was 10 lbs by the 3rd week when he went to our vets it did not fit and he weighed 20.1 lbs It would not clip around his chest. it was about an 1/2 inch to small to clip comfortably around his chest. I could have clipped it but it would have hurt. I measured it around and it measures 21 inches. Hope this helps. Thanks for asking