What Is Pupillary Distance: How Do You Measure It?

Posted by Bridget Reed on

The prescription you have from your eye doctor is confusing enough on its own. Now that you’re ready to shop for lenses and frames somewhere other than their showroom, it can become even more confusing.

You’ll need to know your pupillary distance to make the right purchase, and your doctor may or may not have recorded that on your script. Don’t worry—the Stoggles team has you covered. We’ll explain what pupillary distance is, why it’s important, and how to DIY your measurement at home so you can shop for the frames you want.

What Is Pupillary Distance?

Pupillary distance is the measure between your left eye and your right eye; specifically, between the center of your left pupil to the center of your right pupil. To get a perfectly fit and customized pair of glasses, you need your eye’s measurement to be accurate.

Why does this matter? It matters because your optician needs to get an accurate measurement to make your prescription fully customized for your eyeballs. If it’s even slightly askew, your “perfect pair” of vision corrective glasses won’t be so perfect after all. 

Prescription eyeglasses should position the optical center of each lens directly over the center of each pupil. If your pupillary distance is measured inaccurately, there’s little chance this will happen, and your vision correction won’t be as accurate.

How Do I Read My Eyeglass Prescription?

To determine whether your optician included your pupillary distance measurement on your prescription, look below the complicated grid of letters and numbers. Beneath the grid, your doctor is able to write additional information.

Your pupillary distance can be found there and may be labeled simply “pd.” The first number is the right eye measurement (OD), and the second number is the left eye measurement (OS). This may be written like "28/31mm."

If you’re curious what the other letters and numbers mean on your script, we can help. Here’s our comprehensive guide on how to read the chart like a professional.

How Is Pupillary Distance Measured?

Pupillary distance is measured in millimeters, so when you see your measurement, you’ll see the abbreviation “mm” by the number.

Fun fact: your eye care professional uses a device called a pupillometer to measure your pupillary distance. We’re not eye doctors, but we’re guessing that provides a more accurate measurement than a simple ruler. 

Average PD Measurements

The average pupillary distance for women is between 53-65 millimeters. For men, the average is between 55-70 millimeters. While the average adult’s PD falls between 53-70mm, kids' PD is typically between 43-58mm.

How Do I Measure Pupillary Distance?

Visiting your doctor is the best way to get an accurate pupillary distance reading. In a pinch—or for just the sake of pure curiosity—you can also measure yourself at home. Here’s how.

DIY Pupillary Distance

You can easily measure your pupillary distance at home with a pen and millimeter ruler. Once you’ve got your “specialized” equipment, follow these simple steps to get a (somewhat inaccurate) measure of your own PD.

  1. Stand in front of a mirror, about a foot away from the glass.
  2. Place the end or “0” line of the ruler over one eye and close the other.
  3. Keeping the ruler in place, open the other eye and record the millimeter measurement that is directly over the center of the pupil of that eye.
  4. This measure is your pupillary distance.

If you don’t trust your own ability to measure your pupillary distance properly, there’s an app for that. Apps that use your smartphone camera can give you a fairly good measurement that you can use to order frames and lenses. You can also find apps that use the camera on your tablet or computer.

It goes without saying that your optometrist is going to give you the most accurate measure of your pupillary distance, and it’s worth having yours professionally measured at an eye exam at least once so that you know for the future.

What’s the Difference Between Monocular vs. Binocular Pupillary Distance?

There are two different measurements for the pupillary distance that your optometrist may take. Binocular PD is the measure of the distance between the center of each pupil, like we described above. This is the standard pupillary distance measurement.

"Dual PD" or monocular pupillary distance measures the distance between the pupil of one eye to the center of the bridge of your nose. The combined measure of monocular pupillary distance of both eyes should give you your total binocular pupillary distance, or "single PD."

The monocular PD is taken when you need progressive lenses. Progressive lenses are the new bifocals, giving you both near and farsighted vision correction in a single lens, but without the two-toned look of old-school bifocal prescription glasses. Progressive lenses are smooth and don’t have lines across them like bifocals have.

What’s the Difference Between Far vs. Near Pupillary Distance?

Your eyes naturally shift inward and outward depending on how far away the object is that holds your gaze. If you are looking at something closely like a smartphone or a book, your eyes naturally shift inward. If you are looking into the distance, your eyes shift outward.

The shift is extremely minute, and it’s nearly impossible for you to get this measurement on your own. Your optometrist is the best solution for getting a far PD versus a near PD.

You’ll need these measures if you’re getting progressive lenses, or if you only need glasses to use while reading or driving. For reading glasses, your reading PD will typically be 3mm less than your distance PD.

What If My Pupillary Distance Is Wrong?

It’s rare your doctor would get your pupillary distance measurement wrong, but there’s definitely a chance you could measure incorrectly if you’re doing it yourself. If you do, you’ll likely notice right away when you get your new glasses.

Symptoms of wearing glasses with an incorrect pupillary distance include:

  • Eye strain
  • Fatigue
  • Eye irritation
  • Headache
  • Nausea
  • Blurry vision
  • Inability to focus on objects or words

If you suspect you have an issue with your lenses, you should always contact your optometrist to have your prescription checked and ensure your eyes have been measured correctly.

It’s also important to note that if you’ve been wearing the same prescription and you notice changes in your vision (like the ones above) it could mean that you need a new prescription. Your pupillary distance won’t change as an adult unless you experience an eye injury. 

To make sure that doesn’t happen, you need safety glasses. 

How Do I Measure PD For Safety Glasses?

Pupillary distance measurements are the same for any type of glasses you need because they are specific to your lenses, not your frames. This is why you’re able to shop for frames in places other than your doctor’s office.

In fact, your doctor is legally required to give you your eyeglass prescription so that you can shop for lenses and frames anywhere you like. The Eyeglass Rule is enforced by the FTC, which requires your optometrist to give you a copy of your prescription.

If you need safety glasses, you can get them with corrective lenses if you know where to shop.

How to Buy Prescription Safety Glasses

Just like shopping for your favorite daily frames, you’ll need to shop for safety glasses that fit your style, are available in your prescription, and are comfortable. However, you’ll also need to take into consideration a few other important factors.


Safety glasses should be made of a lightweight, durable material that meets ANSI Z87.1 standards for shatter resistance and impact resistance. This standard places safety glasses under the stress of impact with sharp objects and higher velocities while ensuring the frames don’t break or crack.

For a pair of glasses to pass the ANSI certification, the head form on which the glasses are tested may not have any contact with the object that is launched at the safety glasses, and the lenses and frames must remain non-shattered and intact. This type of high-velocity testing ensures that if your eyewear is struck with a stray rock, pellet, or even fist, it won’t shatter and send shards of dangerous material into your eyes.

Prescription Availability

Not all safety glasses are available with prescription lenses. The ones you find in the bargain bin at the local hardware store aren’t vision-correcting, which means you’ll have to fit them over your eyeglasses. This can be incredibly uncomfortable and distracting.

Stoggles safety glasses are available with your exact prescription, and we handle your prescription lenses in house to save you time and money. Simply take that fancy prescription and upload it to our website, and we’ll take care of the rest, sending you a customized pair of Stoggles with all the bells and whistles. 

UV and Blue Light Protection

Whether you’re a welder or a computer tech, you’re exposed to light that can harm your eyes. Both UV rays and blue light rays are invisible light rays with short, high-energy wavelengths. Your eye has trouble filtering out both types of rays, which means they can pass directly through your cornea right into your retina, potentially damaging your retinal cells.

The highest quality safety glasses—like the ones we offer at Stoggles—will always have blue light protection and UV blocking lenses. 

Another fun fact: the tint on your eyewear does not correlate to UV protection. Your shades can be dark and offer little to no true UV protection. Stoggles eyewear is made from polycarbonate material which is naturally UV-blocking. 

Anti-Fog Coating

You’ve tried anti-fog wipes, so you know they don’t work. Safety glasses that fog place you at a higher risk of having an accident or getting an eye-related injury because they distract you from your task and usually require removal for de-fogging.

Anti-fog lenses keep your eyes focused and ensure you never have to remove your glasses, exposing your eyes to hazards. No anti-fog eyewear is eternal, even coated eyewear must be replaced at some point. Stoggles have an anti-fogging compound sealed onto the lenses at the time of manufacture to keep your lenses fog free for a really, really long time. 

Side and Top Shields

Regular eyeglasses and sunglasses leave your eyes vulnerable in two key places: the space above your eyes near your eyebrows and the space across your temples. To keep these areas safe and offer all-around protection, Stoggles are designed with top and side shields. These shields are low profile, streamlined, and protective. They also work great for corrective lens wearers.

Other options, like wraparound lenses, can sometimes interfere with prescription vision lenses, causing distortion in your vision that looks like a funhouse mirror. In most cases, optometrists will not put an Rx lens into safety glasses — it’s never been done before, and that’s why Stoggles is such a gamechanger when it comes to safety eyewear and prescription lenses.

Style That Is Unexpected

No one goes shopping for safety eyewear expecting much in terms of style, but Stoggles changed the game. Now, you’ve got options, and you get a choice when it comes to protecting your eyes. 

With numerous different frame styles to choose from (including cat-eye and aviator) and a myriad of colors, it’s easy to actually like your safety eyewear and want to wear it. And honestly, if you don’t love your safety eyewear, you probably won’t wear it, which would render it pretty unsafe. 

Why Stoggles Is the Smart Choice

Above all, your safety glasses should be comfortable; otherwise you won’t wear them. Part of being comfortable is feeling good about how you look. Stoggles give you the ability to keep your eyes safe, retain your corrective vision, and look great at the same time. Safety, comfort, style, and accessibility, all wrapped up in one little pair of uber-effective safety specs. Yep, that’s Stoggles! 

Our frames are available in numerous shape and color options, meaning you can truly get a customized fit that works for your face shape and personal style. So, grab your PD measurement and shop for the best safety glasses that keep you comfortable, safe, and effortlessly stylish. Stoggles has the total package.


Complying with the Eyeglass Rule | Federal Trade Commission

Interpupillary Distance (PD) | The Canadian Association of Optometrists

Research Progress About the Effect and Prevention of Blue Light on Eyes | NCBI

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