Ruth, on my wife this covers about half her butt.

26in in size small. I am 5'7" and size small gives me good overage. Very nice fit.

I'm 5'7" with a long torso and am wearing a large. Perfect butt length. Don't know how a small fits @somewhere.

5'5" 112 lbs, 32B. Got XS. If I wanted to layer more than a mid weight fleece or something with a hood, a small might be better. I think you would describe this as hitting at the hip. The XS hits me a good bit below the waist. Don't expect "butt coverage", at least not in an XS, unless you are under 5'. It is cut slim but with good room through the shoulders and upper back. Mountain Hardwear women's stuff tends to run a bit smaller than most outdoor brands. Slimmer cuter lines. Compared with similar products, I would not call this jacket short...or long. The Stretch cohesion pants rock too. Very fitted compared with similar pants with an attached clip belt. I got the XS and they are none too big. Rain pants that look good? Yes.