Measuring your head to get the correct helmet size.

Using a tape measure, measure round your head just above the eyebrows and ears (in centimetres). This is your nominal helmet size. Helmet linings compress, so if your helmet is tight to start with, this is normal. Below there is a helmet sizing and conversion chart.

Helmet Sizing and Conversion Chart

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