What is pupillary distance?

Pupillary distance, or PD, is the distance between the centers of your pupils. Lens makers use it to align the optical centers of glasses with your eyes.

Can I measure PD from a photo?

A photo method can give an estimate if the face is straight, the scale card is visible and pupil centers are clear. It is not a professional fitting measurement.

Why is near PD smaller than distance PD?

When you look at a close object, the eyes converge inward. That usually makes near PD slightly smaller than distance PD.

Pupillary Distance Calculator

Estimate binocular PD, monocular PD and near PD for glasses ordering from manual measurements or a card-calibrated photo method.

Binocular PD, mm

Reading distance, cm

Use separate monocular PD values (left and right known)

What this PD calculator estimates

Pupillary distance is the distance between the centers of the pupils in millimeters. This calculator helps organize measurements for simple glasses-ordering contexts: total distance PD, monocular right/left PD, near PD and a card-calibrated photo estimate.

PD_{p h o t o} = \frac{p x _{p u p i l s}}{p x _{c a r d}} \times 85.60

Photo method using the standard ID-1 card width as the scale reference.

PD_{n e a r} = PD_{f a r} \times \frac{d}{d + 2.7}

Approximate near PD adjustment for close working distance.

Use professional measurements for complex lenses

Progressive, bifocal, pediatric, high-power and prism lenses need measurements from an optician, optometrist or eye care professional, including frame fit and segment height when relevant.

How to avoid common PD mistakes

Measurement	When it is used
Distance PD	Single-vision distance glasses.
Near PD	Reading glasses and close work.
Monocular PD	Separate right and left values, often needed for stronger or more precise lenses.
Photo estimate	A rough check when a professional measurement is not available.

Repeat any home measurement several times. If results differ by more than 1 to 2 mm, or if the glasses are for a child or complex prescription, do not rely on a home estimate alone.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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