How to Measure Your Pupillary Distance (PD)

This post is also available in: Français (French)

Before you order a pair of prescription glasses online, it’s essential to have your pupillary distance (or PD) measurement. 

As part of your glasses prescription, PD helps ensure you to see clearly when you put on your new pair of glasses.

Without the right PD, you might experience eye strain and headaches because they’re not the right fit for your vision.

What is PD in glasses?

PD is the distance between the centre of your pupils, measured in millimetres (mm).

Your PD ensures that your prescription is properly focused and centred. It indicates the optical centre of your eyes, to make sure that your correction is right in front of your pupils. 

It’s important that your PD should be as accurate as possible to make sure you get the clearest and most accurate vision.

If you don’t know what your PD is, you can measure it by yourself with our quick guide below.

5 easy steps to measure your PD

Whenever possible, we recommend getting your PD measurement from your eye care professional. But don’t worry if they didn’t include it on your glasses prescription – it’s easy to measure PD by yourself.

Just make sure to take your time and do it at least twice, to ensure it’s accurate.

Follow the instructions below to measure your PD at home.

1. You’ll need a ruler with millimetre measurements and a mirror or a friend.
2. If using a mirror, try to look straight ahead and into the distance as you measure. If a friend is taking your measurements, try to look past them (straight ahead) into the distance to avoid the result being too narrow.
3. Rest the ruler against the bridge of your nose and line up the middle of your left pupil with the zero line on the ruler. You can now measure the distance between your pupils.
4. Measure across to the middle of your right pupil, still looking into the distance. The average PD for adult women ranges from 46mm to 65mm; adult men ranges from 59mm to 74mm.
5. Repeat these steps two to three times to get a consistent number.

🚨 Quick tip: If your ruler is in centimetres, you can convert it online, but don’t measure your PD in inches. It might result in a wrong conversion and your measurement won’t be accurate. If you measure your PD the wrong way, you won’t have the right lens placement.

3 simple steps to measure dual PD

Dual PD is also known as monocular PD. It is the distance between one pupil to the centre of your nose bridge. It comprises of two measurements and is generally indicated as ‘30(left)/33(right)’.

1. Place the zero line of the ruler at the centre of your nose bridge.
2. Measure the distance between your nose bridge to the centre of your left pupil.
3. Repeat the same procedure with your right pupil.

🚨 Quick tips:

• Ask a friend: measuring your PD on your own might be a little tricky, so having a friend will be easier.
• Hold still: the more still your eyes are, the more accurate the result.
• Ask your optician to measure your dual PD if you want the most accurate results.

Where can I find my PD?

When shopping for your next pair of glasses, it’s important to have all your prescription details handy to make the process quick and easy.

If you have recently visited your eye doctor for an eye exam, you can find your PD on your prescription. If it was not provided, that opens up two possibilities.

First, there’s a chance your prescription is for contact lenses, which is different than eyeglasses. The measurements between contacts and glasses are different.

Learn more about how to read glasses and contact lens prescriptions.

Second, if you do have a glasses prescription but still can’t find your PD, the number may be missing because your optometrist or optician simply didn’t pass it on to you, as they would take care of it when you shopped in store. We recommend that you contact your eye doctor to see if they kept this measurement on file for you before you DIY.

Find your perfect pair

After measuring your pupillary distance, have fun figuring out what colours, frame size, and glasses shape you like best using our Virtual Try-On feature.

Now that you know how to measure your pupillary distance, you’re ready to shop glasses online. Just have your prescription ready and make sure your measurements are accurate before you start the process.

Click here to learn more about buying glasses online.

Have more questions? Contact us by email, live chat or call 1-866-414-2326.