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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 Pupillary Distance?

Pupillary distance, or PD, refers to the distance in millimeters between the center of one pupil to the center of the other. Having a correct PD on your vision prescription ensures that you’re looking through the ideal spot in your lenses.

If this number wasn’t provided on your prescription by an eye care professional, you can measure it yourself at home. Download and print our PD ruler, then follow the simple steps to measure your pupillary distance.

How to measure PD

How to Measure PD

If you're using our PD ruler on someone else (or they're using it on you), fold it to the side that says “Using a friend.” Have them sit down and focus on something 10 to 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. The number above the center of their left pupil is their PD. When measuring, it may help to close one of your eyes so you can read the precise number.

How to Measure PD by Yourself

Measuring your pupillary distance is fairly simple, even if you're alone. All you need is our PD ruler and a mirror. Once you have what you need, follow the steps below:

Measure PD yourself

Fold the ruler, then flip it to the side that says “Using a mirror.”
Stand about 8 inches in front of a mirror. Hold the ruler horizontally over your eyes and center the zero directly over your left pupil. If needed, you can hold the ruler against your forehead for added stability.
Cover or close your left eye. The number directly over your right pupil is your pupillary distance.
How to read a prescription

You may want to relax, then remeasure a few times so you get the most accurate number. If you get different numbers each time, use the average as your final measurement. For example, if you measured your PD five times, add together all five of the numbers you got. Once you have that number, divide it by five. This will give you your final, or average, PD.

If you need progressive or bifocal lenses, you’ll also need to measure your near focus PD. You will need someone else to measure this for you to get the most accurate reading.

The person measuring should follow the same instructions as they would to get your regular PD. However, instead of focusing on an object 10 to 20 feet away, hold a pen between you and the measurer and focus on it. While you do this, the measurer can read and mark down your PD.

How Do I Find My PD for Glasses?

Your PD is important to ensuring a particular point of the lenses goes directly over your pupils. This is especially true for people with high-powered lenses.

Your pupillary distance may or may not be included on your vision prescription. However, it's normally 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 PD for Women and Men?

The average PD for women and men falls somewhere between 48 mm and 73 mm. Women have an average of around 60 mm, while the average for men is about 64 mm. However, pupillary distance is different for everyone.

Single vs. Dual PD

Single pupillary distance is the measurement between the center of one pupil to the center of the other. Dual PD is the distance between the center of each pupil to the middle of the nose. The two numbers in a dual PD represent each of those distances, with the right eye’s PD appearing first.


What is 'PD'?

In addition to the various mobile apps that can measure PD using your phone’s camera, Eyebuydirect has a tool that can do this. When entering your glasses prescription, simply press the ‘i’ button in the PD section.

How do I measure my PD without a ruler?

In addition to the various mobile apps that can measure PD using your phone’s camera, Eyebuydirect has a tool that can do this. When entering your glasses prescription, simply press the ‘i’ button in the PD section.

Can I find my PD on my glasses?

You won't usually find your PD written (or etched) on your glasses. The numbers you see inside your frame’s arms are the measurements for the frame itself, but not your personal pupillary distance. An eye care professional should provide a PD number on your vision prescription in the corresponding section.

Does my PD have to be exact?

Your PD should be exact. If your lenses aren’t centered correctly, wearing them may be uncomfortable. A small margin of error may not cause problems, but it’s better to be as accurate as possible.

Where is my PD on my prescription?

Your PD will be in the ‘PD’ or ‘pupillary distance’ section of your 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?

Your vision is centered on a small section of your lenses, and the PD is used to shape the lenses to accommodate this. If your lenses aren’t properly centered based on your pupillary distance, they can cause dizziness, headaches, and/or blurred vision.

Does PD affect frame size?

Your pupillary distance influences the shape of your lenses, but it has no effect on the size of your frames.

Does PD change over time?

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

Is PD important for single vision glasses?

Your pupillary distance indicates exactly which part of the lens you look through; therefore, the PD measurement is important for every type of prescription, including glasses with single-vision lenses.

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 prescription eyewear because your eyes should be looking through the exact center of your corrective lenses. However, pupillary distance is not necessary if you’re ordering non-prescription sunglasses.

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.