Pet Cage

There is a saying that it is to choose a cage that is three times larger than a dog's body, but how can it be three times as large? If it is calculated from the volume, the upper and the corner of the cage are actually unusable space for the dog. . Others say that just enough dog to turn the width can be. I personally think it's relatively simple. The choice of size is that the length of the cage is twice the length of the dog, which should be more suitable for dogs.