Choosing a frame online becomes easier when three elements are considered separately: size, bridge and shape. Shape mainly defines the visual character of the glasses, while measurements and contact points affect stability and comfort.
This guide explains how to read the numbers shown on product pages and compare them with a pair that already fits well. It does not replace an in-person fitting or professional adjustment, but it helps avoid choosing only by appearance.
The three most common measurements
Inside the temple or on a product page you will often find three values in millimetres, for example 48–21–145:
- 48 mm: width of one lens.
- 21 mm: bridge width.
- 145 mm: temple length.
These numbers do not describe the whole frame. Two models with the same lens width can have very different overall widths because of the rims, hinges and front shape. When available, total frame width is therefore especially useful.
Total width and proportion
A frame that is too narrow may press at the temples or force the arms outward; one that is too wide may slide and feel unstable. Compare the total width with a comfortable pair by measuring the front from one outer edge to the other.
Proportion is also an aesthetic choice. An oversized design may be intentionally wide, but it should still rest securely rather than rely only on pressure from the temples.
The bridge: number and geometry
Bridge width shows the distance between the lenses, but it does not fully explain how the frame will sit on the nose. Keyhole bridges, saddle bridges, adjustable nose pads and different curves distribute weight in different ways.
If a bridge leaves marks, slips repeatedly or places the lenses too close to the eyes, geometry may matter more than the printed number. Adjustable pads offer more scope for fitting, while a solid acetate bridge needs a suitable starting shape.
Temple length and opening
The temples should reach the ears without pulling or feeling unstable. The printed length does not describe every end curve or the lateral opening. Hinges, front thickness and professional adjustment also influence the result.
Face shape: a useful reference, not a rule
Labels such as round, oval or square face can provide ideas, but they are not laws. A frame can create contrast or echo the lines of the face; both approaches can work when proportion, bridge and personality are coherent.
It is often more useful to ask how prominent the glasses should be, where the upper line sits in relation to the eyebrows and how colour works with skin tone, hair and everyday use.
How to compare a frame online
- Take a pair that you already wear comfortably.
- Read the numbers inside the temple or measure the lens, bridge and front.
- Compare the total width, not only the lens width.
- Check the material and bridge type.
- Review front and side images and all colour variants.
- If measurements are missing or your prescription is complex, ask for assistance before ordering.
Material changes both weight and frame behaviour: continue with our guide to titanium, acetate, horn and composite eyewear materials.
Frequently asked questions
Does size 50 mean a large frame?
Not necessarily. It usually refers to lens width; shape, bridge, rim thickness and total width can still vary considerably.
Should I choose a frame only by face shape?
Face shape is a reference rather than a rule. Fit, proportion and personal expression are more important.
Can a frame be adjusted after purchase?
Many frames allow professional adjustment, but the available methods and limits depend on their material and construction.
Compare the measurements on Frank Lo product pages or contact us for help with proportion, bridge and fit.
