We had been looking at and trying on helmets for about a year and most companies start their sizing about 20.5 in head circumference. We were even told to use the padding from regular bike helmets to create a smaller internal size though these options are not supported by the helmet maker companies. My 7 year old measures 19.5 in. So for the last two years she has not been able to go out on the motorcycle with her Dad or her Grandfather. Finally, I found typhoon helmets, specifically made for children, with smaller sizes offered. We ended up trying two sizes since she was right on the border between the medium and the large. If you are like us, this helmet is for you! Buy the smaller size the child borders. The helmet fit perfectly without being too snug, tight, or uncomfortable. There was even still wiggle room for her to grow without needing to go up in size immediately. Since these helmets are made for children specifically they are much lighter and do not fatigue their necks like most helmets. My daughter loved the style and is so glad to finally be out on the open road with her Dad! Thanks typhoon for offering these child specific helmets that are DOT certified!!!! So glad to have found you at last!