Contact or go to the vet's office or animal shelter and ask for measurements. I went to my vet's office with a tape measure and measured all the 4 different sizes they had. But since my vet calls me the unoffical humane society of my county, they know me so well they didn't have a problem with me measuring their kennels. If you vet or animal shelter doesn't want people in their kennel area, they will have to give you the measurements. Also, ask if there are certain materials they want and more importantly, DON'T want in the kennel quilt or pad.