I ordered the i play swim Diaper in white before i ordered this one. My son wears a 2t in clothes so I ordered a 2t in the white diaper. When I received it, it was smaller then i thought so when i ordered this ultimate swim whales diaper, I went 2 sizes bigger to make up for it.  i ordered a 4t for my son who is a 2t in clothes... this diaper barely fits!  i use it as an overnight/nap diaper because he is potty trained and only has accidents on occasion.  When he sees it, he cries because he doesn't want to wear it.  He cries when I put it on and take it off and it leaves an imprint on him from the legs and waist being so tight. Its ridiculous! i only put it on twice because of how much he hates it.  i decided to try it as a swim diaper since I figured maybe it would get bigger in water.. NOPE! Still WAY too small. I wish i could get a refund, I can not use this diaper and it was a waste of money. I am so disappointed because its a great product and would work great if it fit!