Definitely size down, I wear a size large in most things, but still referred to the size chart just in case, I was kinda on the cusp with the the hip measurements between a medium and a large, and on a whim I got the medium and thank goodness because they would be falling of me otherwise :( so everything was too big which was really disappointing due to the to no returns on intimate clothing, which I completely understand, and still give it 4 stars because the product is super cute, the seamwork looks good so I'm assuming it's durable and the material is so soft, like it would be really comfy if it fit me proper!