MICHAEL / Eyewear Answers & Calculators

How do I convert Single PD to Dual PD if my doctor didn't write it down?

Direct answer:Divide a Single binocular PD (50.0–80.0 mm) by 2 to get symmetrical right and left values for mild single-vision prescriptions (for example, 63 mm equals 31.5 mm OD and 31.5 mm OS); if your prescription exceeds ±4.00 D, includes high astigmatism, or uses progressive multifocal lenses, request or measure separate Dual monocular PD numbers (17.5–41.0 mm per eye) instead of dividing.

Use the instant single ↔ dual pd converter below ↓ Check Rx Rules Next →
Interactive PD & Progressive Tool

Single ↔ Dual PD Converter & Progressive Frame Matcher

Convert between Single Binocular PD (50.0–82.0 mm) and Dual Monocular PD (17.5–41.0 mm per eye in 0.5 mm steps), verify standard package limits (≤ 80 mm), and browse progressive-friendly EM frames.

When Dividing Single PD by 2 Works (and When It Does Not)

Single PD vs. Dual PD accuracy guidance and MICHAEL Optical configurator bounds
Prescription TypeRecommended PD FormatAccepted Input BoundsWhy It Matters
Mild Single Vision (within ±3.75 D)Single PD or Dual PD50.0–80.0 mm standard packageA 0.5–1.0 mm facial asymmetry induces negligible prism at low powers.
Strong Single Vision (±4.00 D+) or High CYLDual Monocular PD17.5–41.0 mm per eye (0.5 mm steps)Strong high-index lenses create unwanted prism strain if off-center.
Progressive Multifocal (ADD +0.50 to +3.50)Dual Monocular PD17.5–41.0 mm per eye (total ≤ 80 mm)Keeps the narrow intermediate and reading corridor centered as eyes converge.
Simple Magnification ReadersSingle PD (or Near PD)50.0–80.0 mm standard packageIf your doctor wrote both Distance and Near PD (e.g., 64/61), enter the smaller number (61) for dedicated Readers, and the larger Distance number (64) for Progressives.

Three Reliable Ways to Get Your Exact PD Without Guessing

  1. Check a previous online eyewear order or call your optical shop: Even when an optometrist leaves PD off the paper exam slip, any shop that previously made glasses for you recorded your Single or Dual PD in your patient chart.
  2. Millimetre ruler + mirror check (with a friend): Stand 8 inches from a mirror or have a friend hold a flat millimetre ruler steady across your brow, close one eye at a time to eliminate parallax, and read the distance from the center of your nose bridge to each pupil center twice to confirm repeatability within 0.5 mm.
  3. Confirm package range if above 80 mm: While our form accepts 50.0–82.0 mm Single PD, standard online lens blanks cover total PD up to 80.0 mm; email michael.optical.csr@gmail.com before ordering if your measured PD is 80.5–82.0 mm.

Follow-Up Questions Buyers Ask

My prescription says 63/60 under PD. Which number do I enter?

63 mm is your Distance PD and 60 mm is your Near PD. Enter 63 mm for Single Vision distance glasses, Driving glasses, Sunglasses and Progressive Multifocal glasses (our lab automatically insets the near corridor from your distance PD). Enter 60 mm only when ordering dedicated single-vision Reading glasses.

Why do my Dual PD numbers add up to an odd half-millimetre like 31.5 and 32.0?

Human faces are naturally slightly asymmetrical. One eye often sits 0.5 mm to 1.5 mm farther from the center of the nose bridge than the other, which is why our Dual PD selector supports 0.5 mm increments from 17.5 mm to 41.0 mm per eye.

Can I just use the 63 mm adult average PD to place my order now?

We strongly advise against guessing an average PD, especially on prescriptions stronger than ±2.00 D or any progressive lens. Taking two minutes to call your last optical shop or measure carefully with a millimetre ruler prevents eye strain and remakes.

Clinical & Regulatory References