How to measure sunglasses: temple, bridge and lens width explained

Short answer: To measure sunglasses, read the three numbers on the inside of the temple – for example 51□19-143. They are lens width, bridge width and temple length in millimetres. Then measure the total frame width of a pair that already fits you and compare it with the frame width of the pair you want. That one number tells you more about fit than any “small, medium, large” label.

What the three numbers on the temple mean

Fold out the arms and look inside one of them. Most frames carry a code like 51□19-143. The order is always the same:

• Lens width (51 mm): the width of one lens at its widest point. Also called eye size. It sets how much of your face the lenses cover.
• Bridge width (19 mm): the gap between the two lenses, across your nose. Opticians call it DBL, distance between lenses. It is measured lens edge to lens edge, not across the bridge piece you can see.
• Temple length (143 mm): the arm from the hinge to the tip, including the bend behind your ear.

The small square between the first two numbers simply separates lens and bridge. Some brands use a dash or a space instead. The example above is our Venturi Black wayfarer.

The number that isn’t printed: total frame width

Here is the catch: the code does not tell you how wide the whole frame is. Lens + bridge + lens gives you 121 mm for Venturi, but the real frame is wider, because the rims and hinges add width on both sides. Two frames with very different codes can end up just as wide.

That is why most of our product pages list the full frame width as TTT (temple to temple): the space between the inner sides of the two arms – the space the frame leaves for your head. Too narrow and it presses at the temples. Too wide and it slides down your nose. Our size guide explains each measurement in more detail.

How to measure a pair you already own

The most reliable method is to copy a pair you already like wearing. You need a ruler with millimetres – plastic is kinder to the lenses than metal.

1. Read the code. Check the inside of both arms (and sometimes the bridge). Write down the three numbers.
2. Measure the frame width. Open the arms, turn the pair upside down on a table and measure straight across from the inner side of one hinge area to the other.
3. Measure the lens. If the code has worn off, measure one lens horizontally at its widest point.
4. Measure the bridge. Measure the shortest gap between the two lenses.
5. Measure the temple. Measure from the hinge to the bend, then from the bend to the tip, and add the two.

Lens height is not part of the code. If coverage matters to you – bright beach days, low winter sun – measure your current lenses top to bottom too and look for a frame with similar or deeper lenses.

No pair to copy? Measure your face

Stand in front of a mirror and hold a ruler straight across your face, level with your eyes. Read the distance from one temple to the other, just in front of your ears. Compare that number with the frame width on the product page: a frame within a few millimetres of it is a good place to start. A bank card is 85.6 mm wide if you need a quick sense of scale.

Measurements decide fit; the shape decides the look. For that part, see which sunglasses suit your face.

ECO SHADES sizes from small to large

Some real numbers from our product pages, from narrow to wide:

• Perini Brown – round, Small/Medium: 47□22-145, frame width 130 mm.
• Venturi Black – wayfarer, Medium: 51□19-143, frame width 137 mm.
• Lai Grey – aviator, Medium: 57□17-145, frame width 137 mm.
• Palazzo Havana – rectangular, Medium/Large: 54□24-150, frame width 145 mm.

Look at Lai and Venturi: Lai has much bigger lenses (57 vs 51 mm) and a narrower bridge, yet both frames are 137 mm wide. That is exactly why lens width alone is a poor size guide. Compare the frame width first, then the bridge for your nose and the temple for your ears.

Browse all sunglasses or our recycled sunglasses and open the specs on each product page – every pair has UV400 lenses (see what UV400 means). Can’t find a measurement? Contact us and we will help you with the numbers.

Signs the size is wrong

• Pressure at the temples or red marks: the frame is too narrow, or the temples are too short.
• Slides down your nose: the frame is too wide or the bridge too wide for your nose.
• Pinches the nose or sits high: the bridge is too narrow.
• Arms stick out past your ears: the temples are too long.
• Eyelashes touch the lenses: the frame sits too close – a different bridge often helps.

Good build helps a frame keep its fit over time: hinges that stay tight, temples that sit level. More in how to spot quality sunglasses.

Quick FAQ

Where are the measurements on sunglasses?

Usually on the inside of one temple arm, sometimes on the inside of the bridge. Some brands print the model name on one arm and the size on the other.

What does 52□18-145 mean?

52 mm lens width, 18 mm bridge, 145 mm temple length. It does not include the total frame width.

What is a normal temple length?

Most adult frames have temples between about 135 and 150 mm. Ours are mostly 140–150 mm.

Is lens width the same as frame size?

No. Lens width is one lens. Frame width is the whole front, and that is the number to compare first.