I am 5'4" and weigh 135 (fit body type) and I bought a Medium. Fit great! I was very pleasantly surprised by this skirt. I was expecting a different type of material, but it exceeded my expectations. The material is super light and soft, but also water resistant. I ended up returning it, but only because I purchased it for a trip and never ended up wearing it. Highly recommend this product if you are looking for a swim suit cover up. I would purchase again for sure.