How To Calculate My PD

Definition: Pupillary Distance (PD) is the distance between the centers of your pupils, measured in millimeters.

Purpose: Accurate PD measurement ensures proper lens alignment in eyeglasses for optimal vision correction.

Measurement Methods

1. Professional Measurement: Have an optometrist measure your PD during an eye exam (most accurate method).

2. Mirror Method:

• Stand 8 inches from a mirror
• Hold a ruler against your brow
• Close right eye, align ruler's zero with left pupil center
• Close left eye, read measurement at right pupil center

3. Digital Measurement: Use smartphone apps with facial recognition technology (less accurate).

Understanding Your PD

Average PD Ranges:

• Adults: 54-74 mm
• Children: 43-58 mm

Monocular vs Binocular: Some prescriptions require separate measurements for each eye (common for progressive lenses).

Using the Calculator

Tips: Enter your left and right eye PD measurements (if known separately) or enter half your total PD in each field.

Frequently Asked Questions (FAQ)

Q1: Why is PD important for glasses?
A: Proper PD ensures optical centers align with your pupils for clear, comfortable vision.

Q2: Can I measure my own PD accurately?
A: Self-measurements typically have ±2mm accuracy - professional measurement is recommended.

Q3: Does PD change with age?
A: PD stabilizes in adulthood but may change slightly with facial growth in children.

Q4: What if my eyes have different PDs?
A: This is normal - enter each eye's measurement separately for most accurate results.

Q5: Where can I find my PD on my prescription?
A: Some prescriptions include PD - look for numbers labeled "PD", "DP", or "62/60" format.