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The box measurement system is the industry standard for measuring the size of eyeglass frames. It gets its name because the measurements are taken from an imaginary box drawn around each lens. This system creates a set of simple numbers that tell you the exact dimensions of a frame, which helps you find a pair that fits you well.
read more about box measurement system ...The box measurement system uses three main numbers. The first number is the eye size, which is the width of one lens. The second number is the bridge size, which is the distance of the nose piece between the two lenses. The third number is the temple length, which is the length of the arm from the hinge to the tip. These numbers are always measured in millimeters.
You can usually find these numbers printed on the inside of your current eyeglass frames. Look on the inner side of one of the temple arms or on the inside of the nose bridge. You will typically see a series of numbers like 52-18-140. This would mean the eye size is 52 mm, the bridge size is 18 mm, and the temple length is 140 mm.
Knowing your frame measurements is a great guide for buying new glasses, especially if you are shopping online. It helps you find a new frame that will fit similarly to your old one. A good fit is not just about comfort. It is also needed to make sure the center of the lenses lines up correctly with your pupils, which gives you the clearest vision.
While the standard three numbers (Eye, Bridge, Temple) are printed on the frame, there is a "hidden" fourth number that is vital for progressive lens wearers: the "B" measurement. This is the vertical height of the lens from top to bottom. If the "B" measurement is too small, there may not be enough vertical room in the lens to fit the reading power at the bottom, cutting off your near vision.
The three numbers printed on your frames represent the eye size, bridge size, and temple length in millimeters. They are the standard measurements that define the size of your frame.
No. You can usually go a few millimeters larger or smaller on the eye size and still have a comfortable fit. The bridge size is the most important for comfort, as it determines how the frame sits on your nose.
The total width is not usually printed on the frame, but it is an important measurement for fit. You can calculate a rough total width by adding the two eye size numbers and the bridge size number together (e.g., 52 + 52 + 18 = 122 mm).
While the box measurement system is a very helpful tool, nothing beats having your glasses fitted by a professional. An optician can help you choose a frame that is the right size and shape for your face. This is especially important if you wear progressive lenses, which require very precise measurements to work correctly.
Frame Measurements. American Optometric Association. https://www.aoa.org/a/3209. Accessed March 31, 2026.
Eyeglass Frame Sizes Explained. All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/styles/glasses-frame-size/. Accessed March 31, 2026.
How Should Glasses Fit? All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/fit/right-frames-size/. Accessed March 31, 2026.
How Do I Measure My Glasses? All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/fit/measuring-glasses/. Accessed March 31, 2026.
What Are Asian Fit Glasses? All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/fit/what-are-asian-fit-glasses/. Accessed March 31, 2026.