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How To Find Eyewear Sizes + Measure a Frame

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Dr. Marc Weinstein

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Knowing how to find the perfect fitting pair of glasses may seem difficult. There are so many numbers, measurements, and parts - where do you even start? We want to make sure that you feel confident when ordering your next fabulous frames which is why we put together this helpful guide to understanding glasses and sunglasses measurements!

Eyewear sizes are measured in millimeters or “mm” with a wide range of fits to choose from. The most important measurements that you need to know on any pair of glasses are the lens diameter, bridge width, and temple length. Let’s explore these three terms and learn about what to look for when purchasing your next pair of eyeglasses.

Lens Diameter

Lenses are the plastic or glass portion of glasses that are held by frames in front of the eyes for you to see through. There are many types of lenses including tinted, polarized, and blue light blocking. The lens diameter is the horizontal width of the lens at its widest point. This can also be referred to as your eye size. In most cases, the eye size of frames will be between 44 to 62 mm.

Bridge Width

The bridge of any pair of glasses is the part that rests on your nose in between the lenses. Typically made out of metal or plastic, it joins the lenses together and should feel comfortable and secure when glasses are worn. This piece can be narrow or wide depending on your needs but is typically between 14 and 24 millimeters.

Temple Length

This number measures the length of the stems or “arms” of the glasses. These are the pieces that are secured with a hinge on the side of the frames and go over each ear to keep the glasses in place. These can be made out of a variety of materials and may even include non-slip plastic tips or a head strap for further security. Most temple lengths range from 120 to 150 mm.

If you already own a well-fitting pair of frames you can use them to help find your eyewear size. Look inside the arms or temples of your favorite glasses. You should see three numbers with dashes in between them - for example, 60-15-140. The first number is the measurement of your lens diameter, the second is the bridge width, and the third is your temple length! Use these numbers when picking out your next pair of prescription glasses or sunglasses to find the best fit. You may also see two sets of numbers on the left or right of a square and then a longer separate number. For example 55▫19-140. The first number is still the lens diameter, followed by the bridge width after the square, and finally the temple length.

How To Measure Your Frame Size

The best way to get the correct measurement for your glasses is from an optometrist. Most providers will be happy to measure your eye diameter and pupil distance at any routine ocular checkup. However, if you would rather get a good approximation at home, you can use a straight ruler or even a credit card to measure your lens length.

Most credit cards are 85.60 mm × 53.98 mm or 3 3/8 × ​2 1/8 inches. Simply place the short end of any credit card under your eye and make sure one long side is resting on the middle of your nose.

  • If the outside edge of the card extends to the end of your eyebrow or slightly further than the outside edge of your eye, you will probably fit best in small frames.
  • If the outside edge of the card only reaches the outer corner of your eye or to mid eyebrow, medium frames would probably be best for you.
  • Finally, if the outer edge of the card only reaches mid-eye or closer to your nose, you should probably look for large or extra-large frames.

You can also use a ruler and measure from mid-eyeball to mid-eyeball to find your bridge length or measure the distance between your left and right temple for frame size.

In general, most small frames are between 40-48mm, medium frames are 49-54mm, large frames are 55-58mm, and extra-large frames are anything that is 59mm or above!

We hope this guide to finding your glasses size and how to measure frames helps when shopping on 39dollarglasses.com for your next pair of stylish and affordable eyeglasses!