How to Measure Your PD at Home: A Simple Step-by-Step Guide
Find your pupillary distance in minutes—and get the number you need for ordering glasses online.
Buying glasses online can be convenient, affordable, and surprisingly easy. But before you click “Add to Cart,” there’s one measurement you’ll want to know: your PD, or pupillary distance.
Your PD is the distance between the centers of your pupils, measured in millimetres. It helps position the optical centre of your lenses correctly in front of your eyes.
The good news? You can measure your PD at home with a mirror, a millimetre ruler, and a few minutes of patience.
In this guide, we'll explain exactly what PD means, why it matters, how to measure it yourself, how to measure it with a friend, and what to do if your measurement doesn't seem right.
What Is PD?
PD stands for pupillary distance.
It is the measurement, in millimetres, between the centres of your pupils.
For example, your PD might be 62 mm.
PD is used by an optical professional to help position your lenses correctly within your eyeglass frames. When ordering prescription glasses online, the website may ask you to enter your PD along with your prescription.
Why does PD matter?
Your prescription determines how strong your lenses need to be. Your PD helps determine where those lenses should sit in relation to your eyes.
Getting an accurate measurement is therefore important, particularly when ordering prescription glasses online.
A PD measurement that is entered incorrectly can affect how the optical centres of your lenses line up with your pupils.
Think of it this way:
Your prescription tells your glasses what your eyes need. Your PD helps tell your glasses where those lenses need to sit.
What Do You Need to Measure Your PD at Home?
You don't need fancy equipment. For a basic at-home measurement, you'll need:
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A millimetre ruler
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A mirror
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Good lighting
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Your glasses removed
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A few minutes of patience
A ruler with millimetre markings is ideal because PD is measured in millimetres.
If possible, use a ruler that has a clear, easy-to-read scale.
A quick tip before you start
Don't measure your PD immediately after staring at your phone or computer for a long period.
Take a moment to relax, look straight ahead, and make sure you're comfortable before taking the measurement.
How to Measure Your PD Using a Mirror
This is one of the easiest ways to measure your PD yourself.
Step 1: Stand in front of a mirror
Stand approximately 20 cm (8 inches) away from a mirror.
Use a well-lit room so you can clearly see your eyes and the ruler.
Keep your head straight and look directly into the mirror.
Step 2: Hold the ruler against your brow
Hold the millimetre ruler horizontally across your eyebrows or just above your eyes.
Try to keep the ruler as straight and level as possible.
The ruler should be close enough to your face that you can clearly line it up with your pupils.
Step 3: Close your right eye
Look straight ahead into the mirror with your left eye.
Line up the 0 mm mark on the ruler with the centre of your left pupil.
Take your time with this step.
You want the measurement to start from the centre of one pupil—not the edge of the pupil or the edge of your iris.
Step 4: Open your right eye
Now open your right eye while continuing to look straight ahead.
Look at the ruler and find the measurement that lines up with the centre of your right pupil.
That number is your approximate PD.
Step 5: Repeat the measurement
Don't stop after one measurement.
Take your PD at least 2–3 times and compare the results.
If you consistently get the same number—or numbers that are very close—you can be more confident in your measurement.
If your measurements are significantly different each time, take a break and try again.
How to Measure Your PD With a Friend
Having someone else measure your PD can sometimes make the process easier.
Here's how:
Step 1: Stand facing your friend
Stand comfortably and look straight ahead at a point in the distance.
Don't look at your friend or move your eyes toward the ruler.
Keeping your gaze straight ahead helps your eyes stay in a natural position.
Step 2: Your friend holds the ruler
Have your friend hold a millimetre ruler horizontally across your brow.
The ruler should be positioned close to your face and kept straight.
Step 3: Measure from pupil to pupil
Your friend should measure from the centre of one pupil to the centre of the other pupil.
Record the measurement in millimetres.
Step 4: Repeat
Take the measurement several times.
If you get the same or very similar result each time, that's a good sign that you've taken the measurement consistently.
What Is a Single PD?
A single PD is one number representing the distance between the centres of both pupils.
For example:
PD: 62 mm
This means the distance from the centre of one pupil to the centre of the other is 62 millimetres.
Some online eyewear retailers ask for a single PD measurement.
What Is a Dual PD?
A dual PD, sometimes called a binocular PD or monocular PD, gives you two measurements.
For example:
Right: 31 mm
Left: 31 mm
Or:
Right: 32 mm
Left: 30 mm
The two numbers represent the distance from the centre of each pupil to a reference point, usually the centre of the bridge of the nose.
Why might the numbers be different?
Your face isn't necessarily perfectly symmetrical.
It's completely possible for one eye to be slightly farther from the centre of your nose than the other.
That's one reason some prescriptions or eyewear websites may ask for dual PD instead of a single PD.
If your prescription specifically provides separate right and left PD measurements, use those measurements rather than converting them into a single number unless the retailer specifically tells you to.
Single PD vs. Dual PD: What's the Difference?
Here's the simple version:
TypeExampleWhat It Means
Single PD62 mmOne measurement between both pupils
Dual PD31 / 31 mmSeparate measurement for each eye
Dual PD32 / 30 mmDifferent measurement for each eye
If you're ordering glasses online, follow the measurement format requested by the retailer.
If you're unsure which number to enter, check the retailer's instructions or contact their customer service or an optical professional.
What Is a Normal PD?
PD varies from person to person.
There isn't one single “correct” PD for everyone.
Adults commonly have PD measurements somewhere in the 50–70 mm range, but individual measurements can fall outside that range.
Children generally have smaller PD measurements.
The important thing isn't whether your number looks like someone else's.
The important thing is that your measurement is accurate and consistent.
What If My PD Measurement Seems Wrong?
Don't panic. If your measurement seems unusually high, unusually low, or simply doesn't seem right, measure it again. Here are a few things to check.
Make sure you're using millimetres
PD is normally recorded in millimetres, not centimetres or inches.
Make sure the ruler starts at zero
It sounds obvious, but make sure you're actually using the 0 mm mark as your starting point.
Keep your head straight
Tilting or turning your head can make the measurement harder to take accurately.
Look straight ahead
Don't look at the ruler. Instead, look straight into the mirror or at a fixed point in the distance.
Take multiple measurements
One measurement isn't necessarily enough.
Measure your PD several times and compare your results.
Ask someone else to measure it
If you keep getting inconsistent numbers, ask a friend or family member to help.
Ask an optical professional
If you're still unsure, an optician or other qualified optical professional can measure your PD for you.
Can You Use Your Old Glasses to Find Your PD?
Sometimes your existing eyewear or prescription information may provide your PD, but don't assume the number is printed on the glasses themselves.
Check your prescription paperwork, online eyewear account, or previous order information.
Your PD may be listed as:
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PD
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Pupillary Distance
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Binocular PD
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Monocular PD
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Right/Left PD
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OD/OS PD
If your prescription doesn't include a PD, you can ask your optometrist or optical provider whether they have your measurement on file.
Does Your PD Change?
PD is generally relatively stable in adults, although measurements can vary slightly depending on how and when they are taken.
Small differences can also happen because of measurement technique.
That's why it's useful to take multiple measurements rather than relying on a single attempt.
For children, PD can change as they grow, so a recent measurement is particularly important.
Why Accurate PD Matters When Ordering Glasses Online
Ordering glasses online can be a great way to save time and money, but you're responsible for entering the information correctly.
Your prescription and PD work together to help the eyewear provider position the lenses appropriately.
This becomes especially important with certain types of prescription lenses, including progressive lenses and other more complex lens designs.
If you're ordering prescription eyewear online and you're uncertain about your PD, it's worth getting professional guidance rather than guessing.
A few minutes spent getting the measurement right can save you from the hassle of receiving glasses that don't work as expected.
A Simple PD Measurement Checklist
Before entering your PD when ordering glasses online, make sure you've:
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Used a millimetre ruler
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Measured in good lighting
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Kept your head straight
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Looked straight ahead
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Measured from pupil centre to pupil centre
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Repeated the measurement at least 2–3 times
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Checked whether the retailer wants a single or dual PD
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Compared your measurement with any existing prescription information
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Asked an optical professional if you're unsure
One More Thing: Keep Those New Lenses Crystal Clear
So you've measured your PD.
You've found the perfect frames.
You've ordered your new glasses.
Now comes the part nobody puts on the shopping list: keeping them clean.
Fingerprints, skin oils, dust and everyday grime can quickly turn those beautiful new lenses into two tiny windows covered in fingerprints.
And please don't reach for your shirt.
Your clothing can trap dust and particles that you don't want rubbing across your lenses.
Instead, keep a dedicated microfiber lens cloth with your glasses.
Meet WowyWipe
WowyWipe is a premium, ultra-soft microfiber cloth designed to make cleaning glasses, sunglasses and other delicate lenses simple.
It's designed to tackle everyday fingerprints, oils, dust and smudges without requiring aggressive scrubbing.
And unlike your T-shirt, WowyWipe actually has one job:
Keeping your lenses ridiculously clear.
Use it dry for everyday smudges, or pair it with a lens-safe cleaner when your lenses need a deeper clean.
WowyWipe is great for:
-
👓 Eyeglasses
-
🕶️ Sunglasses
-
📷 Camera lenses
-
📱 Smartphone screens
-
💻 Tablets
-
🔭 Binoculars
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🎿 Ski goggles
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And other delicate optical surfaces
Measure your PD. Find your frames. Then keep them looking crystal clear.
Frequently Asked Questions About Measuring PD
What does PD stand for?
PD stands for pupillary distance. It is the distance, measured in millimetres, between the centres of your pupils.
Can I measure my PD myself?
Yes. You can measure your PD at home using a millimetre ruler and a mirror. For the best consistency, take several measurements and compare the results.
Can someone else measure my PD?
Yes. Having a friend or family member measure your PD while you look straight ahead can be an easy alternative to using a mirror.
Is PD the same for everyone?
No. PD varies from person to person. There is no single PD that is considered normal for everyone.
What is the average adult PD?
Adult PD measurements commonly fall in the 50–70 mm range, although individual measurements can vary.
What is the difference between single PD and dual PD?
A single PD provides one measurement for both eyes, such as 62 mm. A dual PD provides a separate measurement for each eye, such as 31/31 mm or 32/30 mm.
What if my right and left PD measurements are different?
That's possible and isn't necessarily a problem. Faces aren't perfectly symmetrical, so one eye may be slightly farther from the centre of the nose than the other.
If your prescription provides separate measurements, use them as provided.
Do I need my PD to buy glasses online?
Many online eyewear retailers require or request a PD measurement when ordering prescription glasses. The exact requirements vary by retailer and lens type.
Can I use WowyWipe to clean my new glasses?
Absolutely. WowyWipe is designed for cleaning eyeglasses, sunglasses and other delicate optical surfaces. For everyday fingerprints and smudges, it can be used dry.
Final Thoughts
Measuring your PD really isn't as intimidating as it sounds.
Grab a millimetre ruler, find a mirror, make sure you've got some decent lighting, and give yourself a couple of minutes. That's pretty much it.
The trick? Don't rush it. Take the measurement a few times, make sure you're getting roughly the same number, and check whether your eyewear provider wants a single PD or a measurement for each eye.
Once you've got your number, you're one step closer to ordering those new glasses.
And when they arrive?
Please don't clean them on your shirt. 😜
Keep a proper lens cloth handy instead. Your new frames will thank you—and your lenses will stay a whole lot clearer.
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