The easiest way to buy glasses online with confidence is to compare the measurements of a frame you already wear comfortably. Most glasses use three key numbers: lens width, bridge width and temple length.
What do the three frame numbers mean?
You may see a size written as 52–18–145.
- 52 mm lens width: the horizontal width of one lens at its widest point.
- 18 mm bridge width: the distance between the lenses where the frame rests on your nose.
- 145 mm temple length: the length of the arm from the hinge to the end tip.
These measurements are often printed inside one temple arm. If they have rubbed off, use a millimetre ruler and measure a pair that already fits you.
How to measure your current glasses
- Place the frame on a flat surface.
- Measure one lens horizontally at its widest point.
- Measure the narrowest gap between the lenses for the bridge.
- Measure the temple from the hinge to the bend, then to the tip.
- Note the total frame width from the outside edge of one side to the other.
Which measurement matters most?
All three matter, but bridge fit is often the first problem shoppers notice. A bridge that is too wide can slide; one that is too narrow can pinch. Temple length affects whether the arms sit securely behind your ears. Lens width and total width determine how the frame sits across your face.
Can two frames with the same numbers fit differently?
Yes. Frame shape, hinge placement, nose-pad design, material and temple curve all affect fit. Treat measurements as a strong comparison tool, not a guarantee. A 52 mm round lens can feel different from a 52 mm rectangular lens.
How should sunglasses fit?
- Your pupils should sit reasonably close to the centre of the lenses.
- The frame should not rest heavily on your cheeks.
- The temples should not flare sharply outward.
- The bridge should feel secure without pinching.
- The frame should stay in place when you look down.
Use the measurements shown on Aweh product pages when browsing sunglasses, blue light glasses and all frames.
Frequently asked questions
What is a small, medium or large glasses size?
There is no universal size label across every brand. Millimetre measurements are more reliable than S, M or L.
Should the frame touch my eyebrows?
It can sit close, but it should not constantly rub your eyebrows or lift when you smile.
What if I am between sizes?
Compare bridge style and total frame width, then choose the frame closest to a pair you already find comfortable.
Editorial note: Read how Aweh Eyewear prepares product information and evidence-aware eyewear guides.
