Since we work with several designers, we include sizing charts on each product page. If your dog's measurement is on the high end of a range, we recommend going with the larger size especially if the measurements overlap in the sizing. That is what we have found works best for our little doggies. This also helps allow for any additional fluff.
If you are still uncertain, please feel free to contact us via email at email@example.com or via phone at 866.280.1818, and we will do our best to assist you.
Back: Measure from the base of the neck to the base of the tail.
Neck: Measure all the way around the neck at top of the shoulders.
Chest: Measure girth all the way around broadest part of chest or ribcage.
Waist: Measure all the way around the waist.