I’m a medium (32”-34”) and I purchased the large size micro mesh. I sized up because I saw some reviews that suggested that. After purchasing and wearing I do not think sizing up with the micro mesh is the way to go. Also, I don’t like the micro mesh material. A few years ago I bought the Fruit Of The Loom in medium size cotton mesh. I have washed and worn them a lot and they are still in great shape. The micro mesh is made of polyester and spandex/elastane which just just feels cheap and offers almost no support. I did purchase it in the large size but don’t think my opinion would change if I had purchased them in medium size. The cotton mesh is a nice blend of cotton and spandex/elastane. It gives the right amount of support and the material has a softer feel. Plus, you don’t need to size up with the cotton mesh. I think these are excellent underwear at a great price point.