how to measure pupillary distance

At RX Safety, precision and protection converge seamlessly. In the realm of eyewear, Pupil Distance measurement takes center stage. This meticulous process ensures that your prescription eyewear is not just a visual aid but a tailored fit for your unique style and safety needs. Delving into the art of Pupil Distance measurement, we prioritize accuracy and dedication, guaranteeing eyewear that not only enhances your vision but also complements your lifestyle. Join us in prioritizing clarity, comfort, and safety for a distinct and refined optical experience.

What is PupilLARY Distance (or PD for Short)?

It is the distance in millimeters from the center of the pupil of the right eye to the center of the pupil of the left eye. To give you optimum vision, this measurement must be accurate so that the center of the lens is in line with the center of your eye.

Why Pupillary Distance Measurement Is Important: Your eyeglass lenses have an “optical center,” which is the ideal spot for your pupil to look through in order to have optimal vision. Having an accurate Pupil Distance measurement is the key to getting your lenses to line up with your pupils and provide the best possible results from your eyewear.

Single PD vs. Dual PD: Single PD, also known as “binocular PD,” measures the distance from the center of one pupil to the other.

On the other hand, Dual PD accounts for the distance between each pupil’s center and the bridge of the nose. In a dual PD measurement, two numbers are provided—the first for the right eye (OD) and the second for the left eye (OS). This configuration, often written as 31/30, is referred to as “monocular PD” and proves especially useful when selecting progressive lenses.


Pupil Distance Measurement: Typically measured by your optician or eye doctor during an eye exam using a pupillometer, this precise measurement may or may not be included in your prescription. While a pupillometer provides the most accurate Pupil Distance measurement, alternative reliable methods are available, as we’ll explore shortly.

How to Measure Pupil Distance:

Taking charge of your eyewear journey is easier than you think. You have the flexibility to acquire your Pupil Distance in multiple ways—simply request it from your optician during your eye test, measure it yourself using a milimeter ruler, or enlist the help of a friend. If your optician handles the measurement, a crucial step is to confirm that it’s clearly marked on your prescription. This ensures that the information seamlessly integrates into the eyewear customization process, resulting in lenses that align perfectly with your vision needs.

1. Optician’s Expertise

To obtain your Pupil Distance measurement with professional precision, take advantage of your eye test appointment. Simply ask your optician to include this vital measurement during the examination. Their expertise ensures an accurate assessment, laying the groundwork for customized eyewear that caters specifically to your visual needs.

2. Mirror Mastery

You can measure your own PD using a mirror and a millimeter ruler.

STEP 1: Place the ruler flat against your forehead and with your right eye closed, line up the zero on the ruler with the center of your left pupil.
STEP 2: With your left eye closed, take a reading of the ruler at the center of your right pupil.

If you have difficulty seeing what you are doing, then use a magnifying mirror. If it is easier, line up the outside of the iris of one eye with the inside of the iris of the other eye and use that measurement.

3. Friend’s Assistance

For more accurate measuring, you can ask for friends’ assistance. For this method, you will only need a friend and a millimeter ruler.

STEP 1: Looking straight ahead and maintain a steady gaze on an object 10-20 feet away. Keep your eyes still.

STEP 2: Ask your friend to hold the ruler to your browline, aligning the ruler’s 0 mm line with the center of one pupil. Then, locate the ruler’s millimeter line that corresponds to the center of your other pupil. The resulting number is your pupillary distance.

4. Marking Method

You can also consider the DIY Marking Method. Grab a non-permanent felt-tip marker, your glasses, and a millimeter ruler.

STEP 1: With your glasses on, focus on an object at least 20 feet away.

STEP 2: Mark a dot on your right lens on top of the object.

STEP 3: Remove your glasses and use a ruler to measure the distance between the two dots. Align the ruler’s 0 mm line with one dot and locate the corresponding millimeter line on the other dot. The resulting number is your pupillary distance.


5. Online PD Meter

For a versatile online solution, meet Luna at RX Safety — an innovative approach to measuring Pupillary Distance seamlessly during the checkout process. With the Luna PD Tool embedded directly into our website, you can easily obtain accurate measurements as you finalize your eyewear purchase.

This user-friendly online tool simplifies the process: just follow the on-screen prompts, ensure proper lighting, and maintain a straight gaze during calibration.

Luna at RX Safety enhances your experience by providing a convenient and tech-savvy solution, ensuring precision in your Pupillary Distance measurement effortlessly.

Check the Step by Step Guide below.

VIRTUAL PD measurement GUIDE:



RX Safety offers a wide range of glasses frames with prescription lenses. Choose your favorite one.



select prescription type

Inside our prescription form, you can select your prescription type.




Select your preferred lens material and choose extra coatings to upgrade your glasses. This is where you select anti-fog lenses. We also offer special coatings such as anti-scratch and anti-reflective (AR) to improve the overall performance of your glasses.



add your prescription

It is time to upload or fill your prescription information.
For virtual Pupil Distance measurement, click in “GET MY PD” button and follow the next steps.



Pay attention to the audio and video instructions provided. They will guide you through the process step by step.


align your face &
hold a plastic card

Position your face and hold any plastic card against your forehead, following the on-screen image.


your pd measurement
is ready!

After a few seconds, the resulting number is your pupillary distance.

Completing Your Prescription Order Form at RX Safety

Completing your prescription order form at RX Safety is a seamless process, ensuring that your eyewear is tailored to your unique vision needs. If you’re ordering distance or bifocal glasses, it’s essential to provide your Pupil Distance. For those opting for reading glasses, include your near Pupil Distance on the order form. Remember, your near Pupil Distance is typically 3mm less than your distance PD to accommodate the natural convergence of your eyes during reading.

When entering your Pupil Distance measurement, adults typically fall within the range of 54 to 66mm. If, for any reason, you don’t supply your Pupil Distance measurement, rest assured that we’ve got you covered. In such cases, we’ll set the distance optical center at 65mm for men and 63mm for women by default. This ensures that your lenses are precisely aligned, guaranteeing optimal vision correction and comfort. Your journey to personalized eyewear begins with a few key measurements, and we’re here to make the process as smooth and accurate as possible.


How to determine your glasses size

Measuring the
Segment Height

How to measure the segment height

At RX Safety, our commitment to precision extends to default settings, ensuring tailored eyewear even without a specific Pupil Distance measurement. This process is not just about measurement—it’s about crafting eyeglasses that harmonize with individual needs, prioritizing clarity and comfort.

HOW TO Measure Your PD
or better know as Pupil Distance




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