We have measured to the best of our capability but when dealing with soft plush fabric, we can only estimate.
You must have an indication not only when your dog is in full size but also curled up as they will be most of the time when they are snuggled in their bed. If you want your dog to have even more room please order a size up.
If you are still not sure please see below to help you choose the right size, you must measure your dog when it is in its natural sleeping form and take note of the largest width and length that you have measured.
Our sizing "is oversized" because we want your puppy to grow into it. Keep in mind when you are purchasing the SASH bed that it is a bed that is built to last.