FEB 23

Does Pupillary Distance Have to Be Exact?

Pupillary distance – also known as interpupillary distance – is a measure of the distance between a subject’s pupils.

Finding Pupillary Distance

Does Pupillary Distance Have to Be Exact?This measurement is factored into the creation of corrective lenses to help locate the optical center of the lenses. Millimeters are the measurement unit used as the industry standard.

Pupillary distance can be measured by machine – a “corneal reflex pupillometer” – or with a millimeter ruler by any optometrist or optical assistant. It can also be measured by you at home with a small ruler, if you’re careful. The pupillary distance measurement does not have to be 100% precise to be useful, as it can tolerate a fairly small error range. If you do measure your own pupillary distance, it is recommended that you try several attempts to be sure you get a fairly accurate measurement.

To give you an idea of the kind of measurement readings you should get, here are the typical ranges for various groups:

  • Average pupillary distance for an adult is between 54-68mm, with acceptable measurement deviations generally falling in between 48mm and 73mm.
  • The range for children is approximately 41-55mm.
  • The large majority (95 percentile) of adult males in the USA have a pupillary distance of 70mm while a small minority (5 percentile) measure 55mm.
  • The range for adult females in the USA is between 65mm and 53mm.
  • For Europeans the figures equate to roughly 1mm smaller than the above measurements.

Shop Prescription EyewearIf you recently had an eye exam and were given a written prescription, or have an older prescription on file, the prescription may already indicate your pupillary distance. If it does not, you’ll need to obtain that measurement. To do it yourself, follow these steps:

  1. Obtain a millimeter ruler and place it against your eyes, resting on the bridge of your nose.
  2. Line up the 0mm starting point with the outer side of either your left or right pupil.
  3. Look straight ahead and have someone else note the reading, or look directly into a mirror and note the reading yourself. (If using an assistant be sure they are at the same height as you when they record the measurement.)
  4. Once lined up correctly as stated in step 2, the millimeter mark that falls in the center of your opposite pupil is your pupillary distance.
  5. Repeat the process a few times to be sure you get the same result.
  1. Bill W. says:

    My pd was measured 2 yrs. ago by a chain optical store at 32/32. It was measured by mm ruler by the optician, when I purchased my first pair of bifocals (I am 3 yrs. post cataract surgery). After several changes to my rx ( my eyes have 1.25 bilateral astigmatism and my left eye has a sphere of -1.25), I returned to the same store for new glasses. At this time my pd was measured by a digital pupilometer at 29.5/34. Since I had no indication that my previous od was an issue, I opted to go with the original measurement of 32/32. Did I make a big mistake, or is this deviation within a reasonable range of error for my rx?

  2. Tiffani Lowe says:

    My PD in my right eye is 30.2 and my PD in my left eye is 30.3. Only option to choose when ordering glasses is 30 or 30.5 which one should I choose? Will it make a difference?

    • rxsafety says:

      Either way it will be fine But I would go with 30.5 its probably a mistake on the doctors end no one measures to the .1 off a mm on pd. The tolorence for the pd is +/- 3 mm on most prescriptions

  3. Alyssa says:

    Does my PD really matter for simple prescription sunglasses? I’m measuring my PD at 75 mm and I just feel like that’s huge. I have aro

  4. Eric R Norstog says:

    Today I measured pd three ways – one with a ruler measuring my pupils center-to-center at 73 mm; one measuring my old glasses, which could have been anything between 68 and 76 mm, and one measuring the center distance between the ocular lenses of my binoculars, which was 73 mm. Your method says I should put the 0 mm line at the outside edge of the pupil. I started at the middle of the pupil. Will I be OK with 73 mm?

    • rxsafety says:

      Hi Eric,

      Yes you should be ok. For peace of mind, you can also contact your eye dr or the last place you had your glasses made at and they should have this number on file.

  5. Cenk says:

    I measured my Pd value of 70 and ordered glasses, but my doctor measured 67. Does the 3 mm in between cause trouble?

  6. P says:

    My daughters pd 2 years ago at 6 years old was 53 mm I ordered glasses and used the same. I then measured afterward several times with someone else and we got 62mm (now 8 years old) and optical place wouldnt measure for me .. even though I paid for the exam there.. suppose I have to buy glasses there for that step. Will she notice this discrepancy?? I’m not a glasses wearer so I don’t know and want to make sure they are correct. I’ll get them exchanged with my new measurements if so.

    • rxsafety says:


      There is a tolerance window of 3mm when it comes to pupil distance. With that being such a big jump in numbers, there is a chance there could be an issue with the lenses. A lot of places won’t measure your pupil distance unless you are getting glasses done through them. One way you can try to measure your daughter again, is have her put on the glasses she is wearing now, with a washable marker, dot the lenses where her pupils are sitting. Then measure from dot to dot. I hope we were able to assist you. Please feel free to comment more if you have any other questions or concerns.

  7. Josh says:

    the place i got my eye exam says i have Dual PD Rt-30.6 and left 28.7 but most online places only go by .5. Would this make a huge difference? the eye place says yes it will cause blurry site. i’ve seen differing opinions. Would i go up to 29.0 on left or down to 28.5 and 30.5 or 31 for rt?

    • rxsafety says:

      Hi Josh,

      For the right I would go with 30.5 and the left 29. There is a tolerance when it comes to pupil distance. The difference between your numbers is so small, you shouldn’t notice any effect at all.

  8. Marlea Gray says:

    I just ordered a new pair of glasses online. I sent in my PD. RT 32. LT 30. After getting my new classes, I was able to actually have my eyes measured on a machine. (Instead of going by rulers). The right eye was correct, but the left eye was actually 30.5. My question, Is it necessary to have my lenses switched for the 30.5 DP, or can I just keep the ones I already have that the DP is 30? The difference is so slight, that it shouldn’t matter right? Thank you so much for any advice!


    M. Gray

    • rxsafety says:

      Mr Gray,

      A .5 of a mm will not make a difference. The tolerance on PD vary on the power of your cylinder anywhere from 10mm on a to 2mm so your well under the tightest tolerances so you have nothing to worry about.

  9. EDA says:

    What if a near PD and a distance PD are both listed in my RX?

    • rxsafety says:

      Hi Eda,

      That is perfectly fine. When placing an order with our company, you would just provide the distance number first followed by a “/” and then the near PD.

  10. cyndi ball says:

    What PD # do you use when the optician measured 56.5? Do you go with 56 or 57, since PD numbers are whole numbers.

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