Long sleeve romper Jelly Jellyfish 12-18 month We went with the 12-18 month although we are just 8 months so it’s a little big but we wanted to get good use out of it. Used it for our first Florida vacation because our little guys is pretty pale and fair skinned. We also bought the euro shorts and zip in 6-12 month for this summer and they fit true to size. My guy is on the bigger side so the shorts are a little snug but once he starts moving around and walking I think he should slim up and they will be perfect. Fabric is super thick but not hot, soft and comfy. This brand will be our go to bathing suits for summer.