The distance between your eyes, to the millimeter.
A precise pupillary distance reading from your camera — for glasses or VR. Nothing is uploaded, nothing is stored.
11.7 mmiris as reference
0images uploaded
~10 secto a reading
Measure below
Measuring for
Most people don’t need this — the webcam method is easier and more reliable.
Look at the camera — nothing to hold, nothing to aim. It measures automatically. Everything stays on your device.
Here’s what will happen:
Sit about an arm’s length away, with light on your face.
Look at the camera and keep your head straight and level.
Hold still — it captures on its own. You don’t have to click anything.
Tip: good, even lighting and a plain background help. You don’t need a card here — this uses your iris as the ruler.
Your result
Run a measurement and your pupillary distance will appear here.
Everything runs on your device. No image is uploaded or stored.
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What is pupillary distance?
Pupillary distance (PD) is the distance between the centers of your two pupils, measured in millimeters. It tells an optician where to place the optical center of each lens so you look through the correct part of your glasses. Getting it right keeps your vision sharp and comfortable; getting it wrong can cause eye strain, headaches, or blur — especially in stronger prescriptions.
A typical adult PD ranges from about 55 to 75 mm, averaging around 63 mm. PD can be written as a single binocular number (e.g. 63) or as two monocular numbers measured from the bridge of your nose to each pupil (e.g. 31.5/31.5).
How to measure your PD
Pick a mode above — Webcam for a live reading, Photo to upload an image, or Card for the highest accuracy.
Sit about 40–60 cm (16–24 in) from the camera in good, even lighting.
Look straight at the lens, keep your head level, and hold still.
In Webcam mode, just hold still — it captures automatically with a short countdown (or press Measure now). It takes the median of ~30 frames.
Read your binocular PD, plus monocular and near values if you need them.
For the most precise result, use Card mode: hold any standard-size card (any ISO/IEC 7810 card — no credit card needed) in the same plane as your eyes and drag the on-screen markers to its edge to calibrate the scale. It works live with your webcam or from an uploaded photo.
Who needs to measure their PD — and when
Most people go looking for their PD at one specific moment: an online store asks for it at checkout, and the prescription in their hand doesn't have it. That's less an oversight than a division of labour. The eye exam settles your lens powers; PD has traditionally been taken at the dispensing counter, by whoever fits an actual frame to your face. Buy the glasses somewhere else and nobody has measured it yet.
Buying glasses online. The common case, and the one this tool was built for. Almost every online optician has a PD field, and a wrong number there shifts the optical center of each lens away from your pupil — precisely the thing you are paying them to line up.
Reordering from a prescription you already have. A spare pair, prescription sunglasses, or fresh lenses in a frame you like. Your powers are on the paper. Your PD usually isn't — last time, the shop measured it and kept it.
Setting up a VR headset. Headsets call it IPD, but it is the same measurement between the same two points. Most of them let you slide the lenses to match it, and several cover only a limited range — worth checking your number against before you buy one.
Measuring for a child. A child's PD is smaller than an adult's and keeps moving while they grow, so a number from two years ago is not a number to order from.
Checking a value someone else gave you. If a shop measured your PD once and you never saw the figure, or the number on file looks off, measuring at home gives you something to compare against before you commit to a pair of lenses.
There are also cases where you don't need to do this yourself. If you are buying in person, the optician takes the measurement as part of the fitting, so there is nothing for you to do. And if your prescription involves progressive lenses, prism, or high powers, treat any home measurement as a starting point and have it confirmed — progressives also need a fitting height, which no camera-based tool can give you, because it depends on where your pupil sits inside the frame you actually chose.
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How accurate is this tool?
The tool finds 478 facial landmarks (including the iris) and uses a known real-world length as a ruler: either the average iris diameter (~11.7 mm) or, in Card mode, a standard ISO/IEC 7810 card (85.60 mm). In Webcam mode it captures multiple frames and takes the median for stability, and it shows a confidence score based on how steady and well-aligned your head was.
Under good conditions, results are usually within 1–2 mm. Accuracy depends on lighting, image sharpness, and head pose — facing the camera squarely with a level head matters most. Card mode is the most accurate because the reference length is larger and unaffected by eye anatomy.
How this compares to a professional measurement
In a shop, your PD is usually taken one of three ways. With a pupillometer — the binocular device you rest against your brow — which reads the reflection of a small light off each cornea. With a plain PD ruler held against your face, while the optician closes one eye at a time to cancel out their own parallax. Or with a digital centration system, which photographs you wearing the frame you have chosen and measures against a reference clip. The first two measure your face. The third measures your face inside one specific frame.
This tool runs the same geometry as the first two, from a camera, with the iris standing in for the ruler. Under decent conditions it lands close — usually within a millimeter or two. It is worth knowing that the professional number is not a single fixed truth either: a PD taken by two different people, or by the same person twice, does not always come out identical. Manufacturing tolerances for finished lenses exist precisely because small differences are expected.
Where a professional measurement genuinely differs is the fitting, not the number. A centration system measures you wearing the frame, so it captures how that frame actually sits on you — and for progressive lenses it also gives the fitting height, the vertical position of your pupil inside those particular lenses. There is no way to derive that from a photo of a face with no frame on it.
So the honest dividing line runs through your prescription, not through the method. For single-vision lenses in ordinary powers, a careful home measurement is generally enough, and the arithmetic backs that up: a millimeter or two of error in a weak prescription amounts to a fraction of a prism diopter. For progressives, prism, or strong powers, the same error carries real weight, and this tool is a cross-check rather than a substitute.
About this tool
PDMeasure is built and maintained by Mora Tecnologia Ltda. We are not an optician and we are not a store — there is nothing here to buy, no affiliate links to the retailers our guides discuss, and no premium version of the measurement you just took. The site is the tool and the articles, and that is the whole of it.
That shapes how the tool works. Face detection and every calculation run on your own device, inside your browser: no image, no video and no measurement is uploaded, stored, or seen by us. There is no account to create and nothing to install. It also shapes what we are willing to claim — we would rather tell you plainly when a home measurement is not good enough than overstate what a camera can do.
No. All face detection and the entire calculation run locally in your browser using on-device AI. No image, video, or measurement is ever sent to a server or stored.
What is a normal pupillary distance?
Most adults fall between 55 and 75 mm. The average is roughly 64 mm for men and 61 mm for women. Children are smaller — typically around 50 to 61 mm between ages 5 and 15.
What is the difference between single (binocular) and dual (monocular) PD?
Binocular PD is the total distance between the centers of both pupils. Monocular PD is measured from the center of your nose to each pupil separately (for example 31.5/31.5), which matters when your eyes are not perfectly symmetric.
What is near PD?
Near PD is used for reading glasses. Because your eyes converge when focusing up close, near PD is about 3 mm smaller than your distance PD.
Can I measure my PD on a phone?
Yes. The webcam and photo modes work in mobile browsers. Use good, even lighting, hold the phone at eye level, look straight ahead, and keep still.
How accurate is it for ordering glasses?
Under good conditions the result is typically within 1 to 2 mm, which is fine for most single-vision glasses. For high prescriptions, prism, or progressive lenses, confirm with an optician — and use Card mode for the best accuracy.
Where is my PD on my prescription?
Often it isn't there at all. The eye exam determines your lens powers; PD is traditionally measured at the dispensing counter when a frame is fitted, so plenty of prescriptions are handed over without it. If you have had glasses made somewhere, the shop that made them measured it and may still have it on file, which is worth asking about. Otherwise you will need to measure it yourself, which is what this tool is for.
What happens if my PD is a few millimeters off?
The optical center of each lens ends up slightly off your pupil, so you look through a small amount of unintended prism. The amount follows Prentice's rule: the error in centimeters multiplied by the lens power in diopters. Two millimeters of error in a 1.00 D prescription is 0.2 prism diopters per eye, which is negligible. The same two millimeters in a 6.00 D prescription is 1.2, past the usual manufacturing tolerance, and can show up as eye strain or a pulling sensation. The stronger the prescription, the more your PD matters.
Is PD the same as the IPD on a VR headset?
Yes. Interpupillary distance and pupillary distance are the same measurement between the same two points; VR simply borrowed the optical term. Most headsets have a slider or a dial to match the lens spacing to your IPD, and matching it is what keeps the image sharp and comfortable. Some headsets only cover a limited range, so it helps to know your number before buying one.
Does my pupillary distance change over time?
In adults, essentially not. PD is set by the width of your skull and where your eyes sit in it, so once facial growth is finished it stays put and a measurement from a few years ago is still good. In children it does change, because their faces are still growing, so a child's PD should be re-measured rather than reused.
Can I measure my PD without a webcam?
Yes. Photo mode works from an image you already have, as long as you are facing the camera with your head level. Card mode works on an uploaded photo too, if you were holding a standard-size card in the same plane as your eyes. The classic alternative, a millimeter ruler and a mirror, also works, but it is hard to keep the ruler level and your gaze fixed at the same time, and that is where most of the error in that method comes from.
Note: this tool provides an estimate and does not replace a professional eye exam. For high-power, progressive, or prism lenses, confirm your PD with an optometrist or ophthalmologist before ordering.