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How to find your glasses size: a step-by-step guide

Woman wearing sunglasses and holding a phone with sunglasses guide

Size matters when it comes to buying the right pair of glasses. Not sure about what size you need?

Let's find out how to measure your glasses frame size.

If you're not sure how to measure your face shape or how to find glasses and sunglasses that complement your look, read our sunglasses guide!

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1. Learn how to read glasses and sunglasses measurements

Before you write down any numbers, you need to know where to find the size measurements on glasses. So take a closer look at the temples ('arms') of your eyewear if possible.

Inside the temple, you'll find numbers that look like this: 51–19–144.

Those measurements translate as:

  • Lens width (e.g. 51 mm): Lens width is the horizontal diameter of the lens at its widest point. In optometry, another term used for that is 'eye size'.
  • Bridge width (e.g. 19 mm): The bridge is the part that joins the two lenses and sits over the nose. Some refer to this as the 'gap'. The bridge width varies between 14 and 24 millimetres.
  • Temple length (e.g. 144 mm): The temple is the 'arm' that keeps the sunglasses on your face. That 'arm' extends to the part that hooks over the ear. The length is usually 135, 140 or 145 millimetres.
  • Lens height: Lens height is the vertical size of the lens, that is from the top to the bottom of the lens. Although sizes may differ depending on the brand, the standard size is somewhere between 32 and 38 millimetres.
how to read glasses measurements - what is lens width, bridge width and temple lenght

2. Check a pair of old glasses or sunglasses


You can use an old pair of glasses or sunglasses that fit your face perfectly. If you don't have any, try on a pair from a friend to see if they fit you.

If you look closely at the inscriptions on the frames, you'll see numerals that will help you find the right size for your new glasses.

Just keep in mind that each pair of glasses is different and the fit can vary depending on the manufacturer.

Most often, you'll find the size information on the inside of the left temple.

how to read glasses and sunglasses measurements - check a pair of old glasses

3. Measure the glasses and sunglasses size with a ruler

If you can't find any numbers or specifications on your old sunglasses or glasses, don't worry. That just means it's time to test your measuring skills.

Take a ruler or a tape measure and carefully measure the size of the glasses, following the graphic below.

Since too many numbers can get a little confusing, the glasses and sunglasses in Lentiamo's online shop are labelled S (small), M (medium) or L (large), according to the lens width.

how to read glasses measurements - Measure glasses and sunglasses size with a ruler

Once you have the correct measurements, head over to our sunglasses section and find your favourite pair.


4. Use a credit card


Here's another way to use your trust credit card. Did you know that the short side of a credit card is approximately the same as the width of a medium size glasses lens?

Most credit cards measure 85.60 mm × 53.98 mm (3 3⁄8 × ​2 1⁄8 inches)

Here's how to measure with a credit card:

how to read glasses measurements - Measure glasses size with a credit card
  • Take any credit or debit card.
  • Stand in front of a mirror or place your smartphone somewhere steady and use your selfie camera. Place the credit card on the bridge of your nose and under your eyebrow.
  • If the edge of the card extends further than the edge of your eye, you are a small size (size: S)
  • If the edge of the card ends at the outer edge of your eye, you are a medium size (size: M)
  • If the edge of the card ends before the outer edge of your eye, you are a large size (size: L).

Read more

Style advice and tips for choosing the right sunglasses and glasses.