Measure Your Pupillary Distance (PD)
Your pupillary distance (PD) is the measurement in millimeters between the centers of your pupils. It's used to align the optical center of each lens with your eyes, so your prescription glasses are as comfortable and accurate as possible.
Your PD is required for all custom prescription lenses and Extended Vision Reading Glasses. If you don't know yours, you can measure it at home in about 2 minutes.
PD — What It Is and Why We Need It
Prescriptions for eyeglasses are written by an eye doctor and usually include a PD measurement. As the name suggests, it shows how far apart your pupils are from each other. This measurement is crucial because it allows your lenses to be centered correctly in front of your eyes.
PD stands for Pupillary Distance. The lenses in your prescription glasses are made with a specific optical center—the point of ideal clarity. If the optical center is not lined up with your pupil, you may experience blurriness, eyestrain, or headaches.
Your PD is required to produce custom lenses. Most adults have a PD between 58–68mm, with an average around 63mm.
How to Measure Your PD at Home
Gather your tools
You'll need a millimeter ruler (or a printed PD ruler) and access to a mirror. A friend can help, but this is easy to do solo.
Position yourself
Stand approximately 8 inches (20cm) from a mirror, at eye level. Hold the ruler horizontally against your brow, just above your eyes.
Align the zero
Close your right eye. Align the ruler's 0mm mark directly with the center of your left pupil.
Read the measurement
Without moving the ruler, open your right eye and close your left eye. Read the millimeter measurement at the center of your right pupil. That number is your PD.
Measure twice
Repeat the measurement 2–3 times to confirm accuracy. Most people get a consistent result within 1–2mm. Use the average.
Single PD vs. Dual PD
Single PD
A single number representing the total distance between both pupils (e.g., 63mm). This is the most common format and what most orders require.
Dual (Binocular) PD
Two separate measurements — one for each eye from the center of your nose (e.g., 31.5 / 31.5mm). Required for progressive lenses. Usually written as two numbers separated by a slash.
Tips for Accuracy
- Keep your head straight and look directly ahead (not at the ruler).
- Measure in good lighting so your pupils are clearly visible.
- Don't tilt or angle the ruler — keep it level with your brow line.
- If you wear glasses, take them off before measuring.
- Your eye doctor can also provide your PD — ask them to include it on your prescription printout.
Questions about your PD? Contact us at info@lensandframe.co and we'll help you get it right.
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