Ok, so I am a size 16 in clothing (5'8" about 200lbs) and am widest through my hips. I ordered the 1X and it fits like a glove! The sides have a little bit of elastic, so it stretches nicely when you sit down. The straps at the shoulders are adjustable. They are definitely long enough when you sit to go to your ankle, so snow won't go into your boots. It's slightly thinner material than expected, but fair for the price. I'll be able to wear long johns and a hoodie underneath, so I should be all set. Highly recommend.