Use a flexible 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 around the back of your head
Make sure the tape is snug but not tight
Record the measurement in centimeters or inches
Compare the measurement to the helmet brand’s size chart
Choose the helmet size that matches your head measurement
Try the helmet on to check for a secure fit
Adjust the fit system or padding if needed