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How to Measure Pupillary Distance (PD)

Reviewed by : Dr. Matthew Miller, OD on May 19th, 2022

You'll need to know your PD if you want to order new glasses online from Eyebuydirect. Don't worry if your glasses prescription doesn't include your PD, we can show you how to measure it by yourself at home. It’s easy to measure PD online — all you need is a mirror and our printable ruler, available to download below. You can also measure friends’ sizes and have them assist with telling you yours. If you’ve ordered prescription eyewear online with us before, you may have asked yourself, “what’s my PD and how do I measure it?” You can usually find your pupillary distance on your prescription, but if it’s missing, we can help!

How to measure your pd

What is PD?

PD, or pupillary distance, refers to the distance in millimeters between the center of one pupil to the center of the other. Having a correct PD on your glasses prescription ensures that you’re looking through the ideal spot in your lenses, so it’s important to know what is PD. If this number wasn’t provided on your prescription by your eye care professional, you can measure it yourself. So, if you’re wondering how to find pupillary distance, it’s easy to do! Use our printable ruler below then follow the simple steps to find out what yours is. Once you know what pupillary distance is, you’ll be seeing clearly through the correct part of your lenses and never look back!

How to measure PD

How to measure PD

Measuring your PD can easily be done at home. Take our PD ruler and use it on a friend to measure their far distance PD. Fold the ruler to the side that says “Using a friend” and have them sit down and focus on something 10-20 feet ahead to keep their eyes steady. Next, place the PD ruler against their forehead and align the zero with the center of their right pupil and cover your left eye for focus. The number above the center of their left pupil is their PD.

PD measurement online

If you’re alone, it’s also easy to measure pupillary distance online by yourself. All you need is our PD ruler and a mirror. Stand about 8 inches or 20cm away from the mirror and hold the PD ruler over your eyes centering the zero over your left pupil. Cover your left eye and the number directly over your right pupil is your PD. If you’re looking at shopping for progressives or bifocals, you’ll need your near distance PD as well. This time, have a friend help you measure pupillary distance online for the most accurate reading. Instead of focusing on an object 10-20 feet away, have your friend hold a pen between you and them. Focus on the pen and your friend can read your PD.

Measure PD yourself

Place the ruler directly over the center of your right pupil so that the ruler is horizontal. Place against forehead for added stability. Stand in front of a mirror, or ask someone else to measure for you.
While looking straight ahead, measure the distance from the center of your right pupil to the center of your left pupil.
Repeat a couple of times for an accurate PD and use the average pupillary distance for your final measurement.
How to read a prescription

How do I find my PD for glasses?

PD is the distance in millimeters from the center of one pupil to the other. Your PD is an important factor in ensuring the center of each lens of your glasses goes directly over your pupils to cover your eyes correctly. For people with high powered lenses, this is especially important. If your prescription includes your PD, it will normally be listed as one number — 64 for example. If there’s a difference in measurement between the bridge of your nose and the center of each eye, your PD may also appear as two numbers — like 32 and 31. This is your PD separated for each eye.

What's the average pupillary distance for women and men?

What's the average pupillary distance for women and men?

The average pupillary distance for women and men falls somewhere between 48mm and 73mm. The average pupillary distance female and average male pupillary distance considers age and gender. The average PD for women is about 60mm. The average PD for men is about 64mm. However, normal pupillary distance is different for everyone, so the values above can be far from your own PD.

Single PD vs Dual PD

So, what’s the difference between single PD vs dual PD? While single PD is the distance between the center of one pupil to the center of the other, dual PD is the measurement between the center of each pupil to the nose bridge. The two numbers in a dual PD represent each of those distances, with the right eye appearing first. Measuring your PD, or interpupillary distance, is important for knowing which size glasses to get and making sure you’re looking through the correct part of your lenses.


What is ‘pupillary distance’?

Your pupillary distance (PD) is the distance between the centers of your pupils. Your PD is an important part of your prescription because it shows exactly which part of the lens you look through.

How do I measure my PD without a ruler?

There are various mobile apps that can measure your PD using your phone’s camera. You can find EyeBuyDirect’s PD measurement tool by pressing the ‘i’ button in the PD section when entering your prescription.

Can I find my PD on my glasses?

You usually can’t find your PD number written on your eyeglasses. The numbers on the inside of the temple arms of some frames show the measurements for the frame itself. Your PD number should be written on your eyeglass prescription in the PD section.

Does my PD have to be exact?

Your PD should be exact. If your lenses aren’t centered correctly, they can cause discomfort and eye strain. A small margin of error might not cause problems, but it’s better to be as accurate as possible.

Where is my PD on my prescription?

Your PD number will be in the ‘PD’ or ‘pupillary distance’ section of your eyeglass prescription. This is often separate from the ‘grid’ section of your prescription - where the doctor writes out the main prescription information.

What happens if my pupillary distance measurement is off?

If your eyeglass lenses aren’t properly centered based on your PD number they can cause dizziness, headaches or blurred vision. Your vision is centered on a small section of the lenses, so a PD number is needed to shape the lenses to perfectly suit your needs.

Does PD affect frame size?

Your PD has no effect on the size of your eyeglass frame. The PD number influences the shape of your lenses, but not the frame.

Does PD change over time?

A person’s pupillary distance will change when they are young as they are still physically growing. Once we reach maturity and stop growing, our pupillary distance will change very little, if at all.

Is PD important for single vision glasses?

The PD number indicates exactly which part of the lens you look through; therefore, the PD number is important for every type of prescription lens, including single vision glasses.

What is the difference between ‘single’ and ‘dual’ pupillary distance?

A ‘single’ pupillary distance number is the distance in millimeters between one eye’s pupil to the other eye’s pupil. A ‘dual’ pupillary distance number is the distance in millimeters from each eye’s pupil to the center of your nose. A single PD will be just one number, while a dual PD will have a number for each eye, marked ‘right’ and ‘left’. (Some prescriptions may have ‘OD’ for the ‘right’ eye, and ‘OS’ for ‘left’ eye.)

How to find pupillary distance?

You can find out your pupillary distance by either measuring yourself or asking a friend to do it for you. If you’re doing it yourself you’ll need a mirror and you’ll need a ruler regardless. Download our printable ruler or use your own. Just follow the steps on the page above and you’re good to go!

What does PD mean for glasses?

Knowing your PD is important for your glasses because knowing your measurements will help you choose the right size. That means you’ll be looking through the exact center of your lens once you know it and your vision will be crystal clear.

Do you need the PD for sunglasses?

Your PD is important for all eyewear, because your eyes should be looking through the exact center of your lenses. Just because your lenses have a tint doesn’t mean your frame shouldn’t fit properly so knowing your PD is essential.

What is the average pupillary distance?

The average pupillary distance is somewhere between 48mm and 73 mm. However, everyone’s eyes are different and your PD might be different from the average person’s.