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What is Pupillary Distance?

Pupillary distance (PD) is quite simply the distance between your two pupils. Your PD is measured in millimeters and is necessary for creating your custom prescription eyeglasses. Your PD allows an optician to properly position your lenses within a frame of your choice in order for you to see.

Typically, most adults have PDs between 55-65 mm. For kids, PDs are usually between 42-54 mm.

How to Measure PD

You can often get your PD measurement from your doctor or a licensed optician. However, pupillary distance is also easy to measure yourself! With a pupillary distance ruler (in other words, any millimeter ruler), you can measure the distance between the center of your pupils yourself in a mirror or have a friend help out.

3 Simple Steps
Video Guide

1

Place a millimeter ruler on the bridge of your nose.

2

Have a friend face you about arm's length away.

3

Have your friend measure the distance between the center of your pupils (the black dots in the middle of your eyes).

Download A Printable Ruler

How to Measure Your Pupillary Distance

This video explains what a PD (Pupillary Distance) is and how to measure it.

Concerned about you or your friend measuring accurately? We get it - it’s an important measurement, and your eyesight depends on it. That’s why we’ve developed AccuPD.

What is AccuPD?

AccuPD is our free interactive tool that allows you to measure your own pupillary distance right from your phone! The doctors behind 39DollarGlasses.com developed this PD measurement tool as part of our continued efforts to make shopping for prescription glasses easy and affordable.

Getting an accurate PD measurement is now even easier than taking a selfie, thanks to AccuPD from 39DollarGlasses.com. All you’ll need is your smartphone and a credit card (or another card that’s the same size).

Measure Your PD Measure Your PD Measure Your PD

How to Read Pupillary Distance: Single PD vs. Dual PD

Typically, there will only be one number in your PD measurement - this is called Single PD, and it can be used to order most types of prescription eyeglasses.

But if you have two different numbers, you have been measured for Dual PD (also known as monocular PD). In this scenario, the numbers are measurements of the distances from each pupil to the bridge of your nose - the first number refers to the left eye distance, and the second to the right. Added together, these numbers should equal the full distance measured between your two pupils. Dual PD is required for reading glasses, but not usually necessary otherwise.

  • Two of the same number (e.g. 30/30): This is the same as a Single PD measurement between the pupils. When entering this information to order your glasses, you can just add these together and we’ll automatically divide it equally.
  • Two low numbers (e.g. 30/31): The first number is the monocular PD for the right eye (O.D.) and the second number is for the left eye (O.S.).
  • Two high numbers (e.g. 62/59): This is used only for reading glasses. The first number is your Distance PD and the second number is your Near PD.
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About Your Prescription (Rx)

Your prescription provides us with your doctor's recommendation for clear and comfortable vision. Please take a brief moment now to review your information with our 3 samples shown here. They represent 3 different ways of writing the same prescription:

Note, particularly:

01. Your astigmatism correction ("cylinder"). Some doctors write their prescriptions in plus (+) cylinder and some in minus (-) cylinder. They are not the same. Take special note of this when entering your prescription later. If you don't see anything there, leave it blank.

02. "dist" (distance) is often abbreviated "D.V."

03. "near" (reading) is often abbreviated "N.V."

04. For reading-only glasses: Some doctors will write the reading prescription separately, in its entirety (as "NEAR" or "N.V." or "N.V.O."), as in SAMPLE Rx #3. If this is the case, enter the power in the BOTTOM half of the form (you'll see; it's easy), and leave the ADD power blank ("0.00").

If you do not understand ANY part of your prescription, please call us to ensure everything is entered correctly. Don't be shy; we are here to help, and we want your glasses to be made exactly to your doctor's specifications.

OD = Right Eye

OS = Left Eye

OU = Both Eyes

Rx SPH CYL AXIS PRISM ADD
O.D. -1.00 -0.25 005 +2.50
O.S. -1.75 +2.50
Rx SPH CYL AXIS PRISM ADD
O.D. -100 - 25 x 5 + 250
O.S. -175 + 250
Rx SPH CYL AXIS PRISM
Dist O.D. -1.00 -0.25 005
O.S. -1.75
Near O.D. +1.50 -0.25 005
O.S. +0.75
Other Helpful Hints:

01. Your doctor may use a blank Rx pad, not a pre-made Rx pad for eyeglasses only. If this is the case, you can draw imaginary grid-lines to separate the numbers. It will separate the different values more easily for you. The top power is always the right eye & the bottom power is always the left.

02. If you don't see numbers in some of the boxes (if there is no CYL or AXIS or ADD), leave those values blank when ordering. If you only see one number for each eye, it's the "SPHERE" power; leave all the other fields blank.

03. It is common for the doctor to sometimes leave out the decimal points. If you see a number like -25 or +175, it is understood that your doctor means -0.25 or +1.75, respectively. Also, an axis of 5 (or 05) is the same as 005; 90 is the same as 090. It's like using abbreviations or writing in short-hand.

04. If you have no astigmatism in one or both eyes, your doctor may just write the sphere power alone, or may use placeholders like sph ("sphere") or D.S. ("diopters sphere") instead.

05. If you have a prescription for bifocals, and you only see one ADD power, it's understood that you have the same ADD for both eyes. If you don't see an ADD power, leave it blank.

06. Some common prescription abbreviations:

SPH or sph = SPHERE power; the "overall" power

D.S. or DS = diopters sphere (means you have sphere power only)

CYL or cyl = CYLINDER power; the amount of astigmatism

X = axis; X 90 means AXIS 090

ADD = how much power gets added to the distance Rx, for your reading-only Rx or for the bottom half of your bifocals/progressives

Pl or pl or plo = PLANO; it's a placeholder for the number zero

O.D. or OD = right eye

O.S. or OS = left eye

O.U. or OU = both eyes

NV or NVO = near-vision or near-vision-only; your doctor is recommending "reading-only" glasses

P.D. or PD = pupillary distance (the distance in between your right pupil and your left pupil), in millimeters (mm)

-50 = -0.50

+100 = +1.00

If you still do not understand ANY part of your prescription, please contact us to ensure everything is entered correctly. Don't be shy; we are here to help, and we want your glasses to be made exactly to your doctor's specifications.

Your Pupillary Distance (P.D.)

This measurement is necessary to ensure the correct positioning of your lenses within the frame you have chosen. Have a friend* measure the distance from the center of the pupil (black dot) in one eye to the center of the pupil in the other eye. It's like measuring a line connecting the two black dots.

To measure your PD:

01. Place the millimeter ruler on the bridge of your nose.

02. Have a friend face you about arms length away.

03. Have your friend measure the distance between the center of your pupils (the black dots in the middle of your eyes).

04. (Or you can do it yourself simply by looking in the mirror).

You can also get this information from your doctor or from a licensed optician.

As a guideline:

+ Most adults' PD's are between 55-65.

+ Most kids' PD's are between 42-54.