Measure your Pupillary Distance (PD)

Pupillary Distance (PD) is the distance between your pupils.  It may be written as one or two numbers on your prescription. If it's not included on your prescription you can use one of the methods below to measure it.

Use a phone app to measure your PD (easiest)

Glasses On makes a mobile app for iOS and Android devices.  Just download the app and follow the instructions to measure your PD.

Google Play: GlassesOn | Pupils & Lenses - Apps on Google Play

Apple App Store: GlassesOn on the App Store (

Use a ruler to measure your PD

1. Grab a dry erase marker and your glasses
2. While wearing your glasses, look at an object about 20 feet away
3. Have your friend dot each lens directly over your pupil
4. Remove your glasses
5. Measure the distance between the 2 markings with a millimeter ruler for the total PD.  Your total PD measurement in millimeters (ie: 63.5)

Use an online web app to measure your PD

You can use your webcam or phone camera to measure your pd.  The company Vision Works has an online tool you can use to measure.  Check it out here: