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Sizing information

For any person, there is no one right size of glasses. Your face can accommodate a wide variety of glasses sizes and most glasses will work for most people. In order to understand why this is true, you need to look at what size means; size in glasses is a very different concept than size in shoes or clothing. As a result, you should focus most on how the glasses look on your face; when you find glasses that look good, in most cases the glasses can be adjusted to fit your face.

The rule of thumb is that the total width of the glasses front all the way across, including the endpieces, should be similar to the width of your head. This will allow for the optimum proportion of the glasses to the head, and for the best comfort. Follow this link to learn more about how to fit eyeglasses, and follow this link to learn more about choosing glasses for your face shape.

Glasses size

A glasses or sunglasses frame model is usually available in just one size, meaning one combination of eye, bridge, and temple lengths. Occasionally a glasses frame may have more than one size: for example 50-17-135, and 52-17-135, and 54-18-140. You cannot mix and match the measurements, you must take the whole set of measurements for a given glasses frame and you cannot choose a different collection of measurements. For some manufacturers, if a frame model has more than one available temple length, you may be able to swap temples, but you must contact our customer service department to find out if this is possible for the frame you want.


Glasses frames have four basic measurements: the eye, bridge, temple, and B measurements.

The eye size refers to the horizontal width in millimeters of one of the frames lenses. The measurement is taken from the inside of one side of the frame to the inside of the other side of the frame. The lens is measured from its furthest point, where it would intersect with a vertical line.

The bridge measurement is the distance in millimeters between the two lenses. It is measured between the two closest points of the two lenses.

The temple length is measured along the length of the temple, from one end to the other, including the bend. Many frames are constructed with an endpiece that extends from the frame front back along the line of the temple. This backward extension of the frames endpiece could be as little as 2mm, or as much as 15mm. When the endpiece extends further back, the temple length tends to be smaller to compensate. As a result, if you are accustomed to a 145mm temple length, a 135mm temple could work perfectly for you if your new frame has an endpiece that extends back 10mm. This is also the case with many sunglasses with a wrap design. The wrap has the effect of bringing the frame front back towards the ears, thereby requiring shorter temples lengths to compensate.

The B measurement refers to the vertical height of an eyeglasses lens, and is measured from the tip to the bottom of the lens aperture of the frame. The measurements are taken from a horizontal line intersecting with the top of the lens, to the horizontal line intersecting with the bottom edge of the lens. The B measurement is only important when making multifocal lenses; follow this link to read more about progressive lenses.

Reading your glasses size

Most glasses frames have some size information printed on the inside of the frame, although the lettering can be worn away with use. To find all the lettering, you must look on the inside of both temples, and on the inside of the bridge. The numbers usually look something like this:


Eye 50
Bridge 17
Temple 135
Brand/Model # GU125
Color # 635

In this case, the brand Guess is abbreviated GU, followed by the model number of the frame. The eye size is followed by bridge size, sometimes with a small square box in between. The temple length could be printed after the eye and bridge sizes, or elsewhere. Other letters and numbers could refer to the color of the frame. The B measurement is never written on the frame.

Total glasses width

However, these sizes do not give you all the information that you need to know for sure how big the glasses frame is. To know truly how big the frame ismeaning how will it look on your faceyou must determine the total frame width. The total frame width includes the endpieces, and the endpieces are never measured and specified. The endpiece refers to the width of the frame from the edge of the lens out to the edge of the frame where the temples are connected to the frame front.

Once you have determined the total frame width, you can use that value to compare to your current glasses, or you can hold a ruler up to your face to get an idea how well the frame will line up with the sides of your head. Endpieces vary in size from 3mm to 15mm each, which adds up to 6mm to 30mm of the total frame width. The rule of thumb is that endpieces add up to about 10% of the total frame width. Here is the formula to determine the total glasses width:


Total frame width = left endpiece + left eye size + bridge size + right eye size + right endpiece

You can quickly estimate the total frame width by adding the left and right eye size and the bridge size, and then multiplying times 1.1. Because the endpiece sizes are never supplied by the manufacturer, and if you do not have the glasses in your hand to measure, there is a way of more accurately estimating the size of the endpieces online:

  1. Add up left eye size + bridge size + right eye size (= Value A)
  2. Put a ruler up to the photo on your computer monitor to measure the distance of left eye + bridge + right eye (= Value B)
  3. Put a ruler up to the photo on your computer monitor to measure the length of one endpiece (= Value C)
  4. Do some math: A/B = Value D.
  5. Value D times C = Value E
  6. Value E = Real value of one endpiece.
  7. 2E + A = Total frame width

There are some cases where a large glasses frame on a small head could look oversized, and a small glasses frame on a large person may hurt (as the temples persistently dig into the sides of your head). But even in extreme situations, you choose frames first on how they look on your face.

Adjusting your glasses

Almost all eyeglass frames are designed so they can be adjusted. You can take your eyeglass frames to a local optical professional for an adjustment, or read more about adjusting your eyeglasses.

Try on glasses

You may feel that it is necessary to try on glasses before you buy them. However, unlike a shirt that you cannot alter to fit your body, glasses can be adjusted to fit your face. Read more about eyeglasses fit.

We have a liberal return policy, so feel free to order some eye glasses online, and then return the ones that you dont like within thirty days for a full refund (there are some limits here). We do not charge a restocking fee unless you want to order a large number of frames on approval. If you are unsure of a color, or which size of a frame to order, this is a great way to be sure and to see the frames on your face in your own home and take your own time to decide.

We do have an electronic system to try on glasses online that can help you decide. You can upload your own photo and try on glasses online on your own face automatically within seconds (you do not need to email a photo to us), or if you do not have a photo, you can try on glasses on the faces of models heads. The great feature about this system is that after you input your pupillary distance measurement, the system shows you an accurate representation of the size of the frames on your own face. This sizing feature is unique and we have patented it.

Unfortunately, at this time it is not possible to try on glasses online with our system for every pair of glasses in our virtual inventory because we do not have enough photos to support that yet (but we are working on it!). To find out which frames you can try on online, on the product detail page you will see a logo that says e Try It On. On the frame search pages, you will also see a try on this frame link for those frames. If you do not see the logo, then we do not have the image available so that you can do the online try on.