Measure Your Pupillary Distance at Home
Understanding Your PD
Pupillary Distance, commonly called PD, is the distance between the centers of your pupils, measured in millimeters. It helps position each lens correctly in front of your eyes for comfortable, clear vision.
Why an Accurate PD Is Important
- Helps place the optical center of each lens correctly
- Supports clearer and more comfortable vision
- Reduces problems caused by poorly aligned lenses
- Ensures your prescription glasses are made to fit your eyes
Before You Begin
You will need a mirror and a ruler marked in millimeters. Choose a well-lit space and keep your head facing straight ahead.
An adult PD is often around 63 mm, although every person is different. Measure several times instead of relying on a single result.
Step 1: Find the Right Position
Stand approximately 8 inches or 20 centimeters away from a mirror. Hold the millimeter ruler horizontally against your brow or just below your eyes.
Visual guide: Positioning a millimeter ruler correctly while facing a mirror.
Step 2: Set the Starting Point
Close your right eye. Using your left eye, line up the ruler’s 0 mm mark with the center of your left pupil. Keep both the ruler and your head still.
Visual guide: Aligning the zero mark with the center of the left pupil.
Step 3: Find Your Total PD
Open your right eye and close your left eye. Look straight ahead and note the millimeter mark that meets the center of your right pupil. This number is your Total PD, also known as Binocular PD.
Visual guide: Reading the Total PD measurement at the center of the right pupil.
Step 4: Measure Dual PD if Required
Some prescriptions ask for two separate PD numbers. Measure from the center of the bridge of your nose to the center of each pupil.
- OD: Right-eye PD
- OS: Left-eye PD
Add the two measurements together to confirm your Total PD.
Visual guide: Measuring the right and left monocular PD from the nose bridge.
Check Your Measurement
- Repeat the measurement three times
- Use the average if the readings vary slightly
- Keep the ruler level and avoid moving your head
- Ask another person to help if reading the ruler is difficult
- Consult an eye-care professional for children, progressive lenses, complex prescriptions, or uncertain results
