Online Tool Store
Pupillary Distance Measurer
Estimate pupillary distance from a photo using a reference object of known width, then review the measurement limits before ordering glasses.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Health & Fitness
Pupillary Distance Measurer
Frontend preview — no upload or external service.
Estimated PD
Using a card 85.6 mm wide as reference: estimated PD 63 mm, ±2 mm. Dual PD estimated as 31.5 / 31.5, which is often not symmetrical in reality.
How the Pupillary Distance Measurer works
- Photograph yourself straight on, at arm's length, with a standard bank card held flat against your forehead.
- Look at a distant point, not the camera — focusing close pulls the pupils inward and shortens the measurement.
- Treat the result as an estimate; for a strong prescription or progressive lenses, get it measured properly.
The method
A photo gives relative distances; a reference object of known width converts them to millimetres.
PD = (pupil separation in pixels ÷ card width in pixels) × 85.6 mm
A standard payment card is 85.60 mm wide by ISO specification, which is why it works as a scale reference almost anywhere in the world.
FAQ
How accurate is a home measurement?
Typically within a couple of millimetres if done carefully, which is acceptable for a mild single-vision prescription. Progressive and high-power lenses are far less forgiving, and there the error matters.
Why look at a distance rather than the camera?
Because the eyes converge when focusing close, which reduces the measured distance. Distance PD is what most prescriptions specify, so the eyes need to be focused far away.
Should I use single or dual PD?
Dual, if your optician provides it, because faces are rarely symmetrical about the nose bridge. A single PD split evenly assumes a symmetry that often is not there.
How we compare
| Feature | Online Tool Store | A paper log | A subscription health app |
|---|---|---|---|
| Known-width reference | ✓ | Guesswork | Yes |
| States the error margin | ✓ | ✗ | Sometimes |
| Photo stays on your device | ✓ | ✓ | ✗ |
| Optician accuracy | ✗ | ✗ | ✓ |
Pupillary Distance Measurer states its error margin, because two millimetres is fine for a weak single-vision lens and not fine for a progressive one.