How To Measure Your Pupillary Distance (PD)

Knowing your pupillary distance is crucial when choosing the perfect pair of prescription glasses. It’s easy to measure your PD from your couch, so you can simply order your glasses online, without ever having to step foot into a store.

In this post, we will guide you through calculating your pupil distance measurement. Keep reading to find out three easy ways to get this distance, so you can pop it into your prescription order.

What is pupillary distance (PD)?

Quite simply, PD is the distance between your pupils, measured in millimeters. This exact measurement tells the lens maker where to put the optical center on each lens. When ordering glasses online, it is important that you measure this distance accurately so that you can add it to your prescription.

What is my pupillary distance?

There are a few options to measure your PD, so you’re sure to find one to suit you perfectly. You can either wear a pair of glasses, make use of a mirror, or get a friend to help. Here are the three options and their steps to find your pupil distance measurement:

Measuring your PD with glasses on

Step 1: Focus on an object approximately 20 feet away.

Step 2: With a felt pen on each glass, mark over the exact spot where the object is.

Step 3: With both eyes, make sure that the markings overlap into a single dot.

Step 4: Measure the distance between the two dots with a ruler, using millimeters.

Calculate pupillary distance without glasses

Step 1: Stand about 12inches (a ruler’s length) away from a mirror.

Step 2: Hold a ruler up against your eyebrows.

Step 3: Close your right eye and line up the 0mm point with the middle of your left pupil.

Step 4: Open your right eye and close your left, measuring until the center of your right pupil.

Step 5: The mm distance between the centers of your pupils is your pupillary distance.

Calculate your friend's pupillary distance

Step 1: Ask your friend to face you and look straight ahead with both eyes open.

Step 2: Similarly to measuring your own PD, you will now measure between the two centers of your friend's pupils. Ask them to look at something 12 feet away, and not to look at you or move their eyes.

Step 3: Measure the distance between pupils a few times, to ensure that your measurement is accurate.

Calculating near PD for reading glasses

If you are nearsighted, subtract 3mm from your distance PD. For example, if your distance PD is 53mm, then your near PD is 50mm.