Sunglasses | Optical Centre Smartbuyglasess UK

Understanding Glasses Measurement

In the past, shopping for a pair of eyeglasses involved going to our favorite optical shops, fitting in the frames, and when we had found the best pair on the shelf, we used to buy them. Those were the times when we could easily measure eyeglasses but we didn't have many choices.

Then, the modern times have come -- online shops like are established; and as a result, there is an unlimited choice of colors, sizes, and designs for eyeglasses.

Though we have DITTO, the best virtual try-on, we still need to understand the prescription glasses measurements and the frame dimensions. Check our size guide to find out what glasses measurement you need to consider before buying a new frame! 

What do the measurements on glasses mean? 

Engraved at the temples are the glasses measurements. They are represented by three consecutive numbers that are separated by dots, dashes, or vertical bars. They represent respectively the lens width, bridge size, and temple arm length respectively. Some frames even offer the fourth number, which refers to the height of the frames. All these glasses measurements are measured in millimeters (mm).


• Lens width

This refers to the width of the lens, which must be measured horizontally. This usually ranges from 40 mm to 60 mm. Doctors also call it the "eye size."


• Bridge size

This is the distance between the two rims or lenses of the eyeglasses where the nose pads are located. It ranges from 14mm to 24mm.


• Temple arm length

This refers to how long the temple is. Measure temple glasses  from the hinge to the very tip and you’ll come up with the temple length. Normally, it's from 120mm to 150mm.


• Lens height

This is the vertical measurement of the eyeglass lenses. This is important for bi-focal lenses and progressive lenses.


• Frame width

The question “how to measure eyeglass frames?” falls into this section.  The frame width is the horizontal measurement of the frames, including hinges or any designs that stick out at the sides.


It’s much better if you already have an old pair of eyeglasses that fits you well. Just take the measurement and provide 2-3 mm allowances in every aspect except for the bridge size. Coupons on