Your Pupillary Distance (PD) is the distance in millimeters between the centers of your pupils. It’s a vital measurement that ensures your prescription lenses are properly aligned for clear, accurate vision.
At RX Safety, we’ve made it easy to get this measurement — whether you want a fast online tool or prefer to do it manually.
For a quick, easy, and accurate measurement, try Luna, our integrated online PD tool — available both before ordering and seamlessly during checkout at RX Safety.
Why Choose Luna?
Pay attention to the audio and video instructions provided. They will guide you through the process step by step.
Position your face and hold any plastic card against your forehead, following the on-screen image.
After a few seconds, the resulting number is your pupillary distance.
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.
If you’d rather take the measurement yourself, here are three easy ways to do it at home:
What You’ll Need: A mirror and a millimeter ruler
Tip: If lining up the pupils is difficult, you can measure from the outer edge of one iris to the inner edge of the other.
What You’ll Need: A friend and a millimeter ruler
Note: This method tends to be more accurate than doing it solo.
What You’ll Need: Glasses, a non-permanent marker, and a millimeter ruler
Reminder: Clean the marks off your lenses right after measuring.
If you’re unsure which method is right for you, or you’d like help reading your results, the team at RX Safety is happy to assist. Don’t let PD measurement slow down your order — whether you go high-tech with Luna or take the DIY route, we’ve got you covered.
How to determine your glasses size
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.
Fit-over sunglasses have become a popular and cost-effective solution for those who wear prescription glasses and seek enhanced protection from the sun’s harmful UV rays. These sunglasses are designed to fit comfortably…
Whether you are looking to purchase your first pair of glasses or have purchased glasses from some time, you may be concerned about getting the right fit for your new pair. It’s…
In most cases, buying new eyeglasses online is simple. You get your prescription, find the right frames, enter the relevant data points, and wait for the product to be delivered to your…
Stay on top of the latest news about prescription safety glasses, eyewear, sunglasses, and all the trends in the industry.
DISCOVER NOWBe the first one to know about promotion, new products, and more.
Follow Us On Instagram @rx_safety
