Glasses Frames -Our Frame Sizing Information

Steve Mower - June 2020

frametoobig.jpg < Not even close.

Glasses Frames- How to choose the right size eye glass frames.

When shopping for glasses frames, whether for prescription or non prescription, it is really important that you choose one that fits properly. Ideally, the glasses frames should be wide enough so that the temples, or 'arms', go straight back to your ears without putting pressure on the side of your head. That pressure can result in headaches and unsightly dents in your head, and nobody that I know wants dents in their head. Glasses frames should also not be so wide that they slide down your nose all the time.

We use 2 metrics for frame size, the frame fit and the optical eyesize and bridge width:

1. Fit -The frame fit is the way the frame fits on typical face widths. A Medium Fit fits medium width faces. The first thing to pay attention to when shopping our frames is the fit. (There are exceptions to this like folding reading glasses. Folding readers are small by design but in most cases fit wider because they have extended temples and bridges.)

Each style of reader you see on our site is designated by "fit"*:


 Extra Small




Small Medium




Medium Large





Extra Large




*This is a rough guide. The thing is, is that the extension of the temples and the bridge width can make a big difference in the "fit". A 46-22 can fit the same as a 48-18. Both are 114mm across.

2. Optical Frame Size and Bridge Width - This is the way prescription eyeglass frames are sized. All prescription frames are sized based on 3 measurements, in millimeters-

  1. The length or width horizontally, of one lens in millimeters (mm).
  2. The length or width of the bridge, again, in millimeters (mm).
  3. The length of the temples in millimeters (mm).

So a typical size might look like "51-19-135" (lens-bridge-temple usually printed on the inside of the temple) This information is important to opticians but because of the widely different frame styles available, these numbers are fairly meaningless to most eyeglass shoppers. However, knowing what these numbers represent can help you to understand exactly what you are getting, especially in combination with the frame fit. When available we also provide the lens height. The height, or depth as you may, is the mm measurement from top to bottom of the lens.

TIP: You can filter your search for frames by size on our site by Frame Fit and Bridge Width. Choose a frame fit/eyesize and then choose a bridge width. The best way to choose, is to pick a frame size you own, or have tried on that is comfortable for you. Read the numbers on the inside of the temples and search accordingly.

You can also measure the total width of your current eyeglasses in inches. For best accuracy, measure from inside temple to inside temple. Convert to mm below:

A Chart-

ss124 (46K)


Here are 2 handy calculators-

Millimeters to inches-

Convert mm to in


And inches to millimeters-

in to mm calculator




Steve Mower is a licensed Optician and creator of Mojo BluBlock Tints. Steve has over 30 years experience in the optical field. He has been a optical retail manager and has consulted on progressive lens development. Steve has been offering unique reading glasses solutions on-line since 2010.