Use a soft measuring tape
Wrap the tape around the widest part of your head
Place the tape about 1 inch above your eyebrows
Keep the tape level all the way around
Measure over the fullest part at the back of your head
Make sure the tape is snug but not tight
Read the measurement in centimeters or inches
Measure twice to confirm accuracy
Compare your measurement to the helmet size chart
Choose the size that matches your measurement