Measure for the exact product
Neck, chest, body length, paw shape or carrier dimensions may matter depending on the item.
Use the maker's chart
Sizes are not standardized across pet brands.
Check movement and pressure points
A product should not restrict normal movement or breathing or create obvious rubbing.
Recheck growing or changing pets
Puppies, kittens, weight changes and coat changes can make an old size inappropriate.
General product-selection information only. A pet's health, anatomy, mobility, breathing and behaviour can change what equipment is appropriate. Follow product directions and ask a veterinarian or qualified animal-care professional when those issues matter.