How to Measure Pupillary Distance (PD)

How to Measure Pupillary Distance (PD)

PD Quick Box

  • What PD means: The distance (in mm) between the centers of your pupils.
  • Why it matters: It centers your lenses correctly for clearer, more comfortable vision.
  • Most common adult range: 54–74 mm (many people are around 60–66 mm).
  • Single vs Dual PD:
    • Single PD: one number (example: 63 mm)
    • Dual PD: two numbers (example: 31 / 32)
  • Fast accuracy tips: Use a mm ruler, keep it level, measure 2–3 times, use the most repeated result.

Pupillary Distance (PD) is the distance (in millimeters) between the centers of your pupils. It helps ensure your prescription lenses are centered correctly in your frames for clearer, more comfortable vision.

Before You Start

  • Use a millimeter (mm) ruler (best) or a standard ruler with mm markings.
  • Stand in a well-lit room.
  • If you wear glasses, keep them on for the most accurate alignment.
  • Measure 2–3 times and use the most repeated result.

Option 1: Measure Your PD in a Mirror (Single PD)

This is the easiest method if you are measuring by yourself.

  1. Stand about 8–12 inches (20–30 cm) from a mirror.
  2. Hold a mm ruler flat against your brow, just above your eyes.
  3. Close your right eye. Align the ruler’s 0 mm mark with the center of your left pupil.
  4. Keep your head still. Close your left eye and open your right eye.
  5. Read the mm number directly over the center of your right pupil.
  6. That number is your PD (in mm).

Tip: Don’t tilt the ruler. Keep it straight and level.

Option 2: Measure With a Friend (Most Accurate)

If possible, have someone measure for you. Accuracy improves because you can look straight ahead naturally.

  1. Sit facing your friend at arm’s length (about 16 inches / 40 cm).
  2. Look at a point behind your friend (not at the ruler).
  3. Your friend holds the mm ruler across your brow.
  4. They align 0 mm with the center of your left pupil.
  5. They read the mm number at the center of your right pupil.
  6. Repeat 2–3 times and use the most consistent result.

Single PD vs Dual PD (Right / Left)

Single PD is one number (example: 63 mm) measuring pupil-to-pupil.

Dual PD is two numbers (example: 31 / 32) measuring from the center of your nose to each pupil.

How to Get Dual PD (Optional)

If your prescription asks for two numbers, follow the steps below:

  1. Use the friend method if possible.
  2. Measure from the center of your nose bridge to the center of your right pupil (this is Right PD).
  3. Measure from the center of your nose bridge to the center of your left pupil (this is Left PD).
  4. Right PD + Left PD should equal your Single PD (or be off by 1 mm due to rounding).

What Is a “Normal” PD?

Most adults fall somewhere between 54–74 mm. Many people are around 60–66 mm. Children usually have smaller PD values.

Common Mistakes (Avoid These)

  • Using inches: PD must be in millimeters (mm).
  • Tilting the ruler: keep it straight and level.
  • Measuring too close: stay 8–12 inches from the mirror.
  • Not repeating: measure at least 2–3 times.

Already Have Your PD?

Your PD may be printed on your prescription or available from your eye doctor. If you can’t find it, the methods above work well for most customers.

Need Help?

If you want help choosing PD type (single vs dual) or entering it correctly during checkout, contact us via the Contact page or call: +1 (347) 912-6431.

Important: This guide is for general measurement help. For specialty lenses or complex prescriptions, professional measurement may be recommended.