Pupillary Distance (PD) Guide

Getting the right glasses fit is more than picking a frame and lens. One often-overlooked detail is your pupillary distance (PD). It’s a small number. But it directly affects clarity, comfort, and whether your lenses deliver optimal vision.

1. What is PD?

Your Pupillary Distance (PD) is the distance in millimeters between the centers of your pupils (your left and right eye). This number tells the optical lab exactly where your lenses’ “optical centers” must align for you to see clearly.

If PD is off by just a few millimetres, it may cause:

  • Eye strain or fatigue

  • Blurred vision in certain parts of the lens

  • Reduced comfort when wearing glasses for long periods

2. Single vs Dual PD

  • Single PD (Binocular) — one number. Used for many prescription glasses when both eyes are close in measurement.

  • Dual PD (Monocular) — two numbers (one per eye). Important in progressive lenses or if one eye sits significantly further from the nose bridge.

Knowing which type your prescription shows helps you input your PD correctly.

3. Why it matters

When your PD is aligned correctly:

  • The optical centre of each lens sits directly in front of your pupil

  • You get maximum clarity and the full benefit of your lens (single vision or progressive)

When it’s mis-aligned:

  • You may see blur off-centre

  • You may tilt your head or move your glasses to see clearly

  • Over time, your eyes may feel fatigued

The higher your prescription or the more complex your lens (e.g., progressive), the more critical an accurate PD becomes.

4. How to measure your PD at home

Here’s a simple, two-minute method — no special tools required.

What you’ll need:

  • A millimetre ruler or measuring tape

  • A mirror (or a friend to help)

  • A well-lit environment

Step-by-step:

  1. Stand about 8 inches (20 cm) away from a mirror.

  2. Look straight ahead and keep both eyes open.

  3. Place the zero mark of your ruler at the center of your right pupil.

  4. Without moving your head, read the millimeter number aligned with your left pupil.

  5. Repeat the measurement 2–3 times and take the average for accuracy.

  6. If your prescription calls for dual PD, repeat measurements for each eye (to the centre of the nose bridge) and record both numbers.

Smart tips:

  • Remove your glasses if you’re wearing them; lenses can reflect.

  • Ensure your face is level; ask a friend to measure if you’re unsure.

  • Use a credit card width to double-check scale if needed (some sites use this method).

5. Ideal PD ranges & what to expect

Adults typically have PDs in the range of 54 mm to 74 mm.
Children’s PDs are smaller, often between 43 mm and 58 mm.

If your measurement falls outside the typical range, don’t worry — just enter the number accurately. Our lab can accommodate many profiles.

6. What to do if you don’t want to measure

  • Ask your eye doctor to include PD on your prescription. Many do.

  • Use a printed PD ruler (downloadable) from our site or others.

  • Choose a “help me measure” option at checkout (if available) and we’ll guide you or adjust the fit when your glasses arrive.

7. Entering your PD when ordering

In the checkout or lens options:

  • Select the correct lens type (single/distance, reading, progressive)

  • Enter your PD exactly as you measured (either single or two numbers)

  • Double-check before finalising your order

Errors in this step lead to remakes, delays, and frustration. We’ll always check your prescription and PD before production to ensure the best fit.