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How to measure pupillary
distance (PD)

What is PD?

Your Pupillary Distance, or PD, is the distance in millimeters (mm) between the center of one pupil to the center of the other. A personalized fit starts with measuring your pupillary distance: it indicates which part of the lens you look through, ensuring optimal comfort and clarity.

Why is it important?

If your PD isn’t right, it can cause eye strain, fatigue, or simply not being able to see properly. The higher your prescription, the bigger the effect an incorrect PD can have. So get measuring!

What is a single vs dual pupillary distance?

Single PD

SINGLE PD, or binocular pupillary distance is the standard measurement of the distance from the center of one pupil to the other. Distance PD can be used to order any type of prescription glasses except reading glasses.

Dual PD

DUAL PD, or monocular pupillary distance, is the distance from the center of one pupil to the bridge of your nose. Dual PD has two numbers showing the right eye (OD) and the left eye (OS) measurements.

How to find yours

To obtain your PD measurement, simply ask your eye doctor to include it in your prescription.
Alternatively, you can use one of the following methods to measure it yourself. Super easy!

Start using OPTHY

With just a few clicks, OPTHY measures your Pupillary Distance so you get the perfect fit. Discover more

Scan QR Code and download the app.

Download the app.

App available on iPhone X and above.

Problems with the QR Code?
See the app on the App Store.

Meets industry guidelines for accuracy (ANSI Z80.1 and ISO21987 standards)

1 Compatible with single-vision prescription lenses between -5D and +5D.
2 Not intended for use by people under the age of 18.

Glasses Method

What you will need

A pair of glasses

A felt tip marker

A ruler marked in millimeters
(Don’t have one? Download it here)

1. Position yourself

With glasses on, focus on an object 20 feet away or on a close object for near-sighted.

2. Mark your glasses

Mark a dot over the right lens over the object then do the same for the left lens.

3. Measure

Measure the distance between the two dots by aligning the 0 mm line with one dot. The second dot is your PD.

Ruler method

What you will need

A mirror

Pencil & paper

A ruler marked in millimeters
(Don’t have one? Download it here)

1. Position yourself

Position yourself approximately 8 inches (20 cm) away from a mirror.

2. Look in the mirror

Look straight ahead into the mirror and position the ruler over the bridge of your nose.

3. Measure

Close your left eye and align the 0 mm over the center of your right pupil. Measure the distance from your right and left pupil. The number over your left pupil is your PD.

With the help of a friend

What you will need

A friend

Pencil & paper

A ruler marked in millimeters
(Don’t have one? Download it here)

1. Face your friend

Position your friend out of your field of vision. Focus on an object from 10-20 feet away.

2. Center your ruler

Have your friend align the 0 mm over the center of your right pupil.

3. Measure

Measure the distance from your right and left pupil. The number over your left pupil is your PD.

Call 1-800-GLASSES
(800-452-7737)

Monday - Friday: 8:30am - 5:30pm ET
Saturday: 9:00am - 5:30pm ET
Sunday: CLOSED

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Friendly reminder

Print PD ruler at 100% size. Do not use scaling or fit setting. Print setting shoud be actual size.

Measure against a millimeter ruler to assure printout is accurate.

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