How to Measure Pupillary Distance (PD)
When you order glasses online, you'll often be asked for your pupillary distance — the distance between your pupils in millimeters. It's crucial for centering your lenses correctly. The good news: you can measure it at home in minutes.
What Is PD and Why It Matters
PD ensures the optical center of each lens sits directly in front of your pupil. If it's off, you may experience eye strain, headaches, or blurry vision — even with the correct prescription. Most adults have a PD between 54 and 74 mm.
How to Measure It Yourself
- Stand about 8 inches (20 cm) from a mirror.
- Place a millimeter ruler flat across your brow.
- Close your right eye; align the ruler's zero with the center of your left pupil.
- Close your left eye and open your right; read the number at your right pupil's center.
- Repeat twice to confirm — accuracy matters.
For reading glasses, subtract about 3 mm from your distance PD. For the most precise result, ask your optometrist to include PD on your prescription.
Glasses That Fit Right
Once you know your PD, a well-fitted frame makes all the difference. {link('unisex-reading-glasses', 'Unisex reading glasses')} offer a one-size-fits-most fit, while {link('fashion-reading-glasses', 'fashion reading glasses')} add style without compromising comfort.
For active days, {link('flexible-tr90-full-frame-reading-glasses', 'flexible TR90 frames')} hold their shape and alignment over time.
Get a comfortable, accurate fit. Shop Rongchy readers with free shipping.