Eyeglass frames come in many styles, shapes and sizes. Frame measurements play an important role in sizing, which ensures that the frame fits properly and works with your prescription. Measuring the frame width, or the horizontal distance between the outer edges of the frame, will give you an idea of what size frame will fit comfortably. Frame manufacturers and opticians use millimeters as the universal unit of measurement for making glasses.
things you’ll need:
Ruler with millimeters marked
1 Place your frame on a table or level surface with the arms (earpieces) closed and the lenses facing up. Or open the arms and place the frames with the bottom edges resting on the table.
2 Place the metric ruler on the table, and align the end of the ruler with the right side of the frame at the outer edge, where the hinge is located.
3 Measure the distance to the outer edge of the left side.
4 Note the number on the ruler: this is your frame width. Most frames average 130mm to 150mm, or about 5-1/2 inches.
5 Use this width measurement to size your head for eyeglass frames, and when considering new frames.
Tips & Warnings
If you know the width of a frame, you get an idea of how it will fit by measuring the distance between the outer temples of your face, then adding a few millimeters to each side.