Sunny is 14-1/2" at withers and his length is also 14'1/2". He weighs 19 pounds, and has a 12" neck (a little wiggle room) and his chest is, if I remember 21" allowing for a little fur. It's been hard finding the right size for him for coats (tho he has not worn one yet), since he is pretty slender, yet muscular. You almost have to try them on. For instance, I tried a Puppia harness on him initially and ended up getting an XL size since the line (I guess) is geared to smaller breeds. Other fleece sweaters, etc. are harder unless they are adjustable.
I ended up getting an adorable fleece is lime green and turquoise (I will post when done) and have altered it to fit which meant taking about 3" off from the underside -- as he is pretty slender.
I originally tried Hurtta brand coats and don't get me started on sizing, since Sunny does not seem to fit the preset sizes there either. I think teeny dogs or larger dogs seem to be easier. Good luck.
Always a Sunny Day