ShadesDaddy.com lists Ray-Ban sizes by lens measurement, and its blog, ShadesDaddyBlog.com, provides in-depth sizing information on the Ray-Ban Wayfarers line. Ray-Ban suggests using the measurements printed on previous sunglasses to order new ones that fit similarly.
A lens width of 44 to 46 millimeters generally indicates that a pair of Ray-Ban sunglasses is extra-small or junior-sized. Widths of 47 to 48 millimeters and 49 to 53 millimeters indicate adult small and adult small to medium sizes. The lenses of adult large and extra large Ray-Bans measure 54 to 61 millimeters and 62 millimeters. Ray-Ban imprints the lens size and bridge width on the inside arm or bridge of the glasses.