We're really happy with this swimsuit for our 11 month old! He's at least 25 pounds and over 30" so we went with the 12-18mo size. It'll definitely fit all summer. He had a little room but it wasn't baggy. I love that it zips all the way down and you can open it completely. It made taking a wet swimsuit off much easier. I honestly can't believe there aren't more companies that make this type of swimsuit. While we did still put sunscreen on head to toe, we didn't reapply on his body while he wore the swimsuit and he did not get sunburn, even after going in the water. I absolutely will continue to buy from this business.