My husband and son both wear long johns to bed in the winter, they don't ride up as do normal mens sleeping pants. My husband is 62 185 pounds, 33 waist, 34 inseam.  My son is 52 120 pounds with probably a 32 waist and typically wears a size 16 pant.  I bought them both a medium. They both fit them great despite their different heights/weights. Granted, they fit them differently, but it was the perfect size choice. Perhaps they could be a little longer for my husband, but he always wears them with socks before bed anyway, so hes never complained of cold ankles. Would most certainly certainly purchase again. For the price, they are holding up quite well, many washings and no issues at all.