How to measure your Pupillary Distance (PD)

Your PD, or pupillary distance, is the amount of space between the centers of your two pupils. Take a look around and you'll notice that no two faces are alike—and this is one reason why. Not everyone's eyes are the same distance apart! Getting your PD right will help your eyes focus when corrected by the glasses you wear.

PD Calculator

Use a smartphone camera or computer webcam to help calculate your PD, this can be done anywhere.

Option 2
PD Ruler

While we recommend using the PD calculator, you can also do this. Just print, and you can measure your own PD.

Download PD ruler

Real-Time PD Technology

PD Calculator

How to get your PD

You'll need either a tablet, phone, or laptop computer with a digital camera enabled and the volume up. Next, choose a light colored card with a magnetic strip. Go somewhere with a nice amount of light. Hold the card by the top corner, right above your eyebrows.

Get your measurements down

Using our PD calculator, you can take down your PD measurements by following the instructions. Within just a few moments, you’ll have a number that’s ready to go. If you’re logged into your LensDirect account, your PD will automatically be tagged to your account. If you're not logged in, make sure to write it down.

Print a PD Ruler

PD Ruler

Get ready to measure

If you have a safe ruler without sharp metal edges, you can use one at home. Or, print out our ruler. Just make sure that when you scroll through your printing settings, you use either "No scale" or "actual size" when printing. Otherwise, the measurements can get distorted. Once printed, you’ll have a ruler about the size of an ID that fits in your wallet.

Measuring Time!

When you align the 0 on the ruler right above your right pupil (trying to align it with the center of the pupil), you should be able to follow the ruler to the left eye, align it with the pupil, and read the measurement on the ruler.

Write down your measurements

Once you have a number, write it down right away so you don't forget it. Then, as you browse for glasses online, you'll know your exact PD number. One note: the ruler will give you one solid number (i.e., 64 mm), but if need be, you can split this in half so you have a number for each eye. In that example, you would have 32mm for each eye. Put this information in when you order your frames, and voila! Well-fitting glasses.

Download PD ruler

Want to know something? Frequently Asked Questions

What does pupillary distance mean?

Pupillary distance (PD) is the distance measured in millimeters between the centers of your pupils. This measurement varies from person to person but the average for an adult is about 63 mm.

What is pupillary distance used for?

Pupillary distance is used by opticians to help ensure that the power of the lenses will be in the optimum position for vision correction.

An incorrect PD may result in eye strain, which would require a new PD measurement and replacement of lenses in your glasses. It is especially important when fitting glasses with progressive lenses as it requires very precise lens-to-pupil alignment to ensure vision at all distances.

Does my PD have to be exact?

Yes, your PD must be exact for maximum vision and comfort while wearing your glasses. If your lenses are not sitting in the optimum position to give you vision correction, it can cause eye strain and discomfort over time.

Why do I have to measure my own PD?

You may have to measure your own PD if your eye doctor did not include it on your prescription. PD is required to order glasses accurately online and by taking an online PD measurement you can save a trip to the doctors!

Can I just guess my PD?

No, we do not recommend guessing your PD as it can vary from person to person. Having an incorrect PD will result in eye strain for not having properly aligned lenses.

What happens if my PD is inaccurate?

You can experience eye strain, headaches, fatigue, and blurry vision. Having a high prescription and the wrong PD can make these symptoms worse, we recommend getting your PD measured accurately.

Does PD have any effect on frame size?

PD has no effect on the size of your eyeglass frame; however, it can affect the shape of your lenses.

Do opticians have to give you your PD?

The Federal Trade Commission requires eye doctors across the country to give patients a copy of their prescription for free, however giving pupillary distance is not always included in that prescription, it varies from state to state.

Does pupillary distance change as you get older?

Pupillary distance changes during childhood, but upon reaching adulthood PD remains constant.

What is the difference between single and dual pupillary distance?

There are two primary methods for PD measurement: single PD and dual PD.

The difference is in measurement methods, single PD is the measurement from pupil to pupil between each eye. Dual PD is the measurement from your nose bridge to each of your eyes.