Moby approximately 90lbs (a Weimaraner Lab/Basset Hound mix) and is wearing a size Large.

XS (Back length: 10", Chest: 16", Neck: 12")
S (Back length: 12", Chest: 20", Neck: 14")
M (Back length: 16", Chest: 22", Neck: 18")
L (Back length: 22", Chest: 30", Neck: 22")
XL (Back length: 27", Chest: 30", Neck: 26")