PD for Glasses: What to Enter When You Order
How far apart your pupils are, in mm, is called your PD, and the lab uses it to centre each lens. You will be asked for it on all glasses orders, entered as one figure like 63 or a pair like 31.5/32.
The PD to Put on a Glasses Order
Most order forms offer two ways to enter it. With a single PD, both eyes share one number, for example 63. A dual PD lists one number for each eye, 31.5/32 for example, measured from the centre of your nose, right eye first (Cleveland Clinic). For most single vision glasses, either option works. If you have it, use the dual PD: faces are rarely perfectly even.
Distance PD or Near PD?
Enter your distance PD when ordering glasses for all-day wear or driving. For reading glasses, use a near PD, normally 3 mm smaller (Warby Parker). The near PD calculator figures it out for you. Progressive and bifocal lenses require your distance PD, and a fitting height as well.
Getting the PD Measurement for Glasses
Start with your prescription: the PD box may already include the number. You have three easy options if it is missing:
- Use your camera, along with a bank card, and measure it in roughly a minute.
- Take the reading from a ruler while facing a mirror, or print a PD ruler.
- Phone the eye doctor or optician who performed your eye test. Some states in the US require that the prescription list the PD (FTC Eyeglass Rule).
Measure PD From Old Glasses
When your current glasses feel right, the centres of their lenses already match your PD. While wearing them, look in a mirror at something far away, then mark each lens over the pupil with a washable felt pen. Then measure the space between the two dots. The step-by-step guide explains the full method.
Single PD Glasses vs Dual PD Glasses
With a single PD, each optical centre is placed half that number from the frame's middle. With a dual PD, each optical centre is placed at that eye's own distance. For most people, the difference stays under 1 mm for each eye. If a form wants the other kind, convert between the two.
Is PD Required for Glasses?
Yes, for all prescription glasses. The lab cannot centre the lenses unless it has this number. Mild lenses may work with an average of about 63 mm, but strong or progressive ones cannot. It is not needed for plain sunglasses or for blue light glasses without a prescription.
PD for Glasses Questions
PD on glasses: what does it mean?
Pupillary distance: how far apart the centres of your pupils are, measured in millimetres.
For reading glasses, do I need a PD?
Off-the-shelf readers do not ask for a PD. A near PD is needed for custom reading glasses: take your PD and subtract about 3 mm. Read about near PD.
Which PD value should I enter for computer glasses?
Because a screen is farther away than a book, most people take their distance PD or a figure about 1 to 2 mm smaller.
Is it all right to reuse my PD when I order new glasses?
Yes, if you are an adult. Once you are fully grown, PD stays the same, so an old measurement still works.