What size bike helmet do I need for my child?
What does the size of a child’s bike helmet mean?
The sizes of children’s bike helmets are based on the wearer’s head circumference. This measurement, expressed in centimeters, can be found on any helmet. For instance, if you see 44-48 cm on a helmet, this means the helmet is suitable for children with a head circumference that falls within this range.
Apart from the standard size in cm, most manufacturers use their own sizing. These sizes are often expressed in letters, and range from XXS via medium to L or even XXL. Because these sizes differ per manufacturer, it is best to rely on the head circumference in centimeters.