My child used this for a long time, from kindergarten to upper elementary school. I have many other hats, so I think it was used about 7-8 times. I think it's a size that adults with small heads could also wear. I'm sorry, but there are no measurements in centimeters, so I don't know that. It's a cute knit hat with a pom-pom and nice colors. It will be shipped compressed in simple packaging.