How to know your Frame Size?
1. if you've an existing eyeglass
Find out the Frame Size which will fit you the best from your Lens Width. You can find it inside one of your temples. It is usually a number written between 40 to 70.

Lens Width & Frame Size
Frame Size |
Eyeglasses Lens Width |
|
Small |
Below 51 mm |
Small Eyeglasses >
|
Medium |
51 mm- 54 mm |
Medium Eyeglasses >
|
Large |
Above 54 mm |
Large Eyeglasses >
|
2. if you don't have an existing eyeglass
1. Take a Debit/Credit card

This is the approximate width of a medium Eyeglass, Sunglass
2. Stand in front of a mirror.

Place one tip of the card on center of your nose and touch the other towards the edge of eye.
3. Now check the position of the card: -

If card extends beyond the corner of the eye
Size is SMALL

If card roughly touches the corner of the eye
Size is MEDIUM

If card doesn't reach the corner of the eye
Size is LARGE