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How to read spectacle measurements: a simple and professional guide
What do the numbers on the frame mean, and how do you choose the right size?
Each pair of frames has specific measurements that help you understand how they fit on your face. These numbers are printed on the inside of the temple or the bridge and indicate the lens width, the bridge width and the temple length.
In this guide, we explain in a simple yet professional manner how to interpret these measurements and how to use them to choose the most suitable frames, based on the expertise of the Isolani Opticians.
1. Where can I find the measurements for the glasses?
The measurements are usually marked on the left-hand mast or on the deck. They are given in millimetres and appear in this format:
52 ▢ 18 145
Each number has a specific meaning and helps you understand how the frames will suit your face.
2. Size (lens width)
The first number indicates the width of the lens, known as gauge. This is the horizontal measurement of the lens, excluding the frame.
A larger size means a wider lens and a wider frame.
Example: 52 mm.
3. Bridge (distance between the lenses)
The second number indicates the size of the bridge, that is, the distance between the two lenses. This measurement affects how the glasses sit on the nose.
Example: 18 mm.
4. Shaft length
The third number indicates the shaft length, that is, the section running from the attachment point on the frame to the end of the end piece.
Example: 145 mm.
5. Total width of the frame
The total width is not always stated, but it is one of the most important measurements for determining whether a frame fits well. At Isolani Opticians, we always assess this during the fitting, along with the shape of the face and visual behaviour.
6. How to choose the right size
To choose the right size, you can:
- check the measurements of your current glasses
- compare the gauge, bridge and rod with the new frame
- measure the total width of the frame
- take into account the shape of the face and the fit
A well-proportioned frame ensures comfort, stability and a harmonious look.
If you’d like to find out more about how to choose the right size based on the frame measurements, you can consult our Size Guide, where we also explain the S, M and L sizes used on Isolani.com.
7. Fittings and digital try-on at the Isolani Boutique
At the Isolani Boutique, you can check the measurements of each frame, compare them with those of your current glasses, and filter the models by shape and fit.
8. Isolani’s professional consultancy
At Centri Ottici Isolani, we assess not only your eye measurements, but also your posture, working distance, face shape and actual visual behaviour. Choosing the right frames is a balance between aesthetics, comfort and proportions.
9. Conclusion
Reading your glasses measurements is simple and helps you choose a frame that fits well and flatters your face. If you’d like professional advice, the Isolani Opticians and the online boutique are here to help.