these long johns are VERY warm and VERY comfortable, while still being moderatly thin material (not too bulky). I wear a U.S. size 34" waist, 32"-34" length, I bought a size XXXL (china) and they fit loose. Not baggy, not tight, just... comfortable. The next pair I buy will be a size XXL though, because I do prefer my base layer to fit snug, like leggings, or Under Armor. Quality, fit, shipping, price, all 5 out of 5. I like them a lot.
On height/weight 180/80 small. Under the trousers to wear is not cold, but not comfortable-legs bend unpleasant. In general, it is better to look for a bigger size and that the fabric outside easily slides.