Which Snow Helmet size is best for my head?

To get a better idea of what size best fit's you, let's convert the sizing above to New Era's 59Fifty fit guide as this is one of the most common headwear brands in America:

Small: 53-55cm = 6 5/8th's to 6 7/8th's.

Medium: 55-58cm = 6 7/8th's to 7 1/4th.

Large: 59-61cm = 7 1/2 to 7 5/8th's.

Note that some of the New Era sizing is a little larger than what is listed here and we have aired on the smaller side vs bigger to allow for further fine tuning of fitment