Place your tape measure around your dogs neck where he / she would normally wear their collar.
Ideally the collar should be a snug fit to prevent your dog slipping out of it. But it shouldn't be too tight either.
If your dog is large or medium place two fingers inside the tape measure. If your dog is small use one.
If your dogs neck is larger or smaller than the size of our off the shelf collars please message us using the contact form on he home page to discuss your requirements.