All of our rings are sized in US universal sizes. If you are unsure of your ring size, please order our FREE PAD Ring Sizer first. To find a US size conversion chart, visit our helpful blog post here. We are unable to offer a free size exchange for any ring that is custom or contains gold. The Carbon Fiber Glowstone Ring is NOT eligible for a free size exchange. If your ring does not fit, please email us at email@example.com for options on obtaining a newly sized ring.