A few weeks ago i purchased both my kids running shoes and waterproof hightop shoes (keens with velcro awesome!) so I recently looked at their feet standing on the inserts i remove from shoes to see for growth room. I was super confident based on my knowledge of keens that we own and checking my kids feet I purchased a size larger for both my boys. both my kids sizes 6 (youth) and toddler (10) where at least one full size too small. Note my oldest has wide feet so these were also way too narrow not what i expected from keens. So definitely buy one size up my youngest just grew into a size 9 so a 10 should have been fine. I will say they are much lighter than bogs and way better bogs get all sweaty these liners are great. I think bogs are awful though kids have to drag them get holes in the heel they arent great at all. I was able to open it up nicely and easy for a toddler which i honestly thought looking at the picture these werent toddler friendly. I wont be buying the next size up we opted to buy stonz trek for both the boys. They arent water proof and the rubber isnt as durable as these but they are much lighter and fit wider in the toe box. My two year old actually kept falling over in the house with these and couldnt kick the soccer ball with the weight and gave up walking just cried on the floor but loved the stonz trek.My toddler is a drama prince though so def consider these boots they are the same weight as toddler kamik boots and lighter than sorel toddlers. Cheerios!