Please enter valid measurements for both eyes (typically between 20mm and 45mm).
Your Binocular (Total) PD:
—
Suggested Near PD (for reading glasses): —
What is Pupillary Distance (PD)?
Pupillary Distance (PD) is the measurement of the distance between the centers of your pupils, expressed in millimeters (mm). This measurement is crucial when ordering prescription eyewear because it ensures that the optical center of the lenses aligns perfectly with your pupils. If the PD is incorrect, you may experience eye strain, headaches, or distorted vision.
Types of PD Measurements
Binocular PD: The total distance from the center of one pupil to the center of the other.
Monocular PD: The distance from the bridge of your nose to the center of each individual pupil (e.g., 32mm for the right eye and 31.5mm for the left). This is often more accurate as most faces are slightly asymmetrical.
Near PD: Specifically used for reading glasses. Because our eyes converge (turn inward) when looking at close objects, the Near PD is typically 3mm to 4mm less than the distance PD.
Example Calculation:
If your Right Monocular PD is 31mm and your Left Monocular PD is 32mm: Total PD: 31 + 32 = 63mm Near PD (Reading): 63 – 3 = 60mm
Normal PD Ranges for Adults
While PD varies significantly from person to person, the average adult PD is approximately 63mm. Most adults fall within the 54mm to 74mm range. Children typically have a PD ranging from 43mm to 58mm. If your calculated result falls far outside these ranges, we recommend re-measuring or consulting an eye care professional.
How to Measure PD at Home
If you don't have your monocular measurements from an optometrist, you can measure your total PD with a millimeter ruler and a mirror:
Stand about 8-10 inches away from a mirror.
Hold a millimeter ruler against your brow.
Close your right eye and align the 0mm mark with the center of your left pupil.
Looking straight ahead, open your right eye and close your left eye.
The mark that aligns with the center of your right pupil is your binocular PD.
function calculateTotalPD() {
var leftInput = document.getElementById("leftMonocular").value;
var rightInput = document.getElementById("rightMonocular").value;
var errorDiv = document.getElementById("pdError");
var resultDiv = document.getElementById("pdResultContainer");
var totalPDDisplay = document.getElementById("totalPDResult");
var nearPDDisplay = document.getElementById("nearPDResult");
var left = parseFloat(leftInput);
var right = parseFloat(rightInput);
// Basic validation: Monocular PD is rarely under 20 or over 45 for adults
if (isNaN(left) || isNaN(right) || left 50 || right 50) {
errorDiv.style.display = "block";
resultDiv.style.display = "none";
return;
}
errorDiv.style.display = "none";
var totalPD = left + right;
var nearPD = totalPD – 3; // Standard calculation for reading glasses offset
totalPDDisplay.innerHTML = totalPD.toFixed(1) + " mm";
nearPDDisplay.innerHTML = nearPD.toFixed(1) + " mm";
resultDiv.style.display = "block";
}