Measuring your head to get the correct helmet size.

Using a tape measure or a piece of string, measure round your head just above the eyebrows and ears, as in the diagram, left. Take the measurement obtained in centimetres. This is your nominal helmet size. You may wish to buy a slightly larger or smaller size depending on your personal preference e.g. if you prefer a tighter fit, buy one size smaller. Helmet linings do compress, so if your helmet is slightly tight to start with, this is quite normal. If possible, attempt to try on a helmet of the exact make and model that you require, so that you can be sure to order the correct size. On each helmet page you will see a size and corresponding code which you should use to order your desired helmet size. To assist you, we have included a useful helmet sizing chart and size conversion information below, showing centimetres and inches and UK and US hat sizes.
Helmet Sizing Chart and Conversions

cm inches UK Universal USA
52 20 1/2 to 20 7/8 6 1/2 xx-small 6 5/8
54 21 to 21 1/2 6 5/8 x-small 6 3/4
56 21 3/4 to 22 1/4 6 7/8 small 7
58 22 1/2 to 23 7 1/8 medium 7 1/4
60 23 1/8 to 23 3/4 7 3/8 large 7 1/2
62 24 to 24 5/8 7 5/8 x-large 7 5/8
64 24 7/8 to 25 1/2 7 3/4 xx-large 7 7/8