I'm consistently a size M and these fit just right. These boxer briefs are the best I've found. The material is soft with just the right amount of stretch, and I appreciate that it's 90% merino. These do not ride up. The horizontal fly could use a bit more overlap but doesn't bother me. The waistband, which has been a problem with a lot of other brands for me, doesn't roll. I'll likely buy more once the size and color I want are back in stock.