Find your size
#1 Take a credit card
This is the approximate width of a Standard Size lens.
#2 Stand in front of a mirror
In front of a mirror or a webcam, place one edge of the credit card at the center of your nose. Where does the other edge end?
#3 If note touches the end of the eye
A When the edge of the credit card ends at the end of the eye your fit should be Standard Size
B When it extends well beyond the end of the eye you should get a Small Size
C When the credit card does not reach the end of the eye then go for a Large Size.