Ray-Ban Wayfarers come in standard and large sizes. Ray-Ban offers two styles of Wayfarers: the Original Wayfarer and the New Wayfarer. The Original Wayfarer is the most recognizable of the Wayfarer series. It's slightly larger than the New Wayfarer, and its lens shape isn't as round.
Ray-Ban also offers a line of junior Wayfarers, which have proportionately similar sizing distinctions between the Original Wayfarer and the New Wayfarer.
The measurement on the sunglasses can usually be found on the inside of one of the arms. The lens diameter is printed first, followed by a short dash or square, and then the bridge width.