How to measure your pupillary distance

How to measure your pupillary distance

Your pupillary what?

Pupillary distance (PD for short) is the length, in mm, between the centre of your pupils.

This measurement allows us optical folks to align your prescription lenses with the centre of your eyes.

Frustratingly, your pupillary distance on prescription papers isn’t always stated.

Instead, why not measure your PD yourself?


Free PD ruler by Banton Frameworks 

Measuring your pupillary distance

We've designed and made you a free PD ruler.

It's got a slot for your nose and mirror-friendly numbers.

This makes the job much easier and gives a more accurate result, especially if you're doing this alone.




Man measuring his pupillary distance using an optical PD ruler


Method 1: Using our PD ruler.

  • Download and print your free PD ruler.
  • Locate the V slot over your nose to find your facial centre.
  • Using a mirror, check where your pupil aligns with the mm increments.
  • It's easier to close one eye to see each opposite eye's PD.
  • Note your measurements.


Pro tips

    You may end up with a couple of different measurements.

    • If you need single vision lenses, you’re safe to take the average measurement you get.
    • If you need varifocal lenses, you’ll need to take a more accurate measurement made of two mono PD’s.

    What's a mono PD you ask? Click here



      Man measuring his pupillary distance using a regular ruler


      Method 2. What about a regular ruler?

      Ok cowboy, you can use a regular ruler for this job.

      However, it's pretty fiddly to hold the ruler still on your brow and will probably give you inaccurate results.

      Oh yea, rulers are sharp. Just saying...


      • Steady as you can, hold the ruler across your brow.
      • Point the mm increments downward.
      • Close your right eye then align the 0mm mark with the centre of your left pupil.
      • Look ahead then close your left eye and open your right eye.
      • The mm line that lines up to the centre of your right pupil is your total PD.


      Measure pupillary distance using an old glasses frame an non permanent pen


      Method 3: How to measure pupillary distance using old glasses

      This is a classic move.

      You’ll need help from a friend on this one so it’s good to ask nicely.

      • Grab your old glasses and a non-permanent marker pen.
      • Get your partner to mark a small dot where your pupil is behind the lens.
      • Measure the distance between the dots for your total PD.



        Measuring pupillary distance with a phone app


        Method 4: Mobile app.

        We’ve done the hard work for you.

        Here’s a free pupillary distance app you can download.

        Check it out here



        Find your pupillary distance on your prescription paper


        Method 5: Your prescription may already have it

        Take a good look at your prescription paper.

        Excusably, you might have overlooked your PD as it can sometimes be sneakily tucked away without realising it. It might even be on the reverse-side of the paper.

        If your PD measurement is there, it’ll appear as one or two numbers.

        • If it’s one number, it should be around 64mm or so.
        • If it’s stated as two separate numbers, they should be around 32mm.


        Male or female, your PD size will vary, roughly between a minimum of 58mm and 68mm.



        Young male wearing round tortoise acetate spectacle frame


        How important is the PD for glasses?

        To ensure that the centre of your lens aligns with the centre of your eye, your PD measurement is pretty important.

        It’s safe to say that guessing your PD is a big no no, especially after reading the steps we’ve shown you above.

        But let’s not freak out about this one guys.

        Sure, you don’t want to give us the wrong pupillary distance… but think about it. Your glasses can sit ever slightly ‘off’ on your face so pin-point accuracy is perhaps a little bit overkill.

        Heck, with the instructions above, you know what you’re doing. You’ll nail it.


        Illustraton of single PD and dual PD


        What is single PD and dual PD when ordering glasses?

        Mentioned earlier, your PD can be written as one or two numbers.

        • Single PD = the total distance between the centre of your pupils.
        • Dual PD = the separate distances between the centre of your head and the centre of your pupils.


        Pupillary distance two numbers

        Your prescription paper may use dual PD’s as standard.

        These can be added together, but only if require a PD total. This is usually for single vision glasses wearers.

        However, if you require complex or strong prescription lenses such as varifocals, it’s imperitive that you provide your dual PD's as per each of your eyes.

        This lets us that your lens centres are as accurate to the centre of your pupil as possible. Varifocal glasses have a higher tolerance of accuracy as they are a more complex lens type.

        Generally, total PD’s or average PD’s are considered as insufficient for varifocal prescriptions.

        You can measure your mono PD yourself with a basic ruler, but we suggest you use our free PD ruler which locates onto the centre of your nose for a more accurate result.



        Brunette female wearing tortoise shell spectacles by Banton Frameworks


        My Mono PD’s are slightly different?

        Don’t worry, most people have a slightly asymmetrical head.

        In fact, the most attractive celebrities have facial asymmetry… phew.

        Your mono PD’s will vary ever so slightly. For example, your right eye Mono PD could be 32.5mm and your left eye could be 33mm.  

        This variance is perfectly normal


        White measuring tape on concrete floor


        What is the average PD?

        If you wear single vision glasses, it can be okay to use average PD’s.

        But the problem with average?

        It’s… average.

        You’re better taking a few minutes to get a proper measurement using our advice above. However, if you’re cool with average, here’s the average PD’s for adult men and women.

        • Average PD for men: 64mm
        • Average PD for women: 62mm