All breeds and dogs are built differently. This is a generic guide for measuring your dog. You must have a measuring tape for accurate measurements. My items are made to close with velco which makes them slightly adjustable.(Approximately 1 to 2 inches)
Neck: Snuggly wrap a tape measure around the base of the neck where the collar would sit.

Chest: Snuggly wrap a tape measure around the body at the largest point of the rib cage.

Length: From the base of the neck to the tail.

Bellybands: Snuggly wrap a tape measure around belly over his piddler.

Female Diapers and Diaper Skirts: Meaure from A to B to C. This will be the length of the diaper. Measure from A to B ( just under the tail ). Measure around the girth of the dog just in front of the hip bone A to C.