- Print our downloadable PD ruler
- Place the ruler directly over the center of your right pupil so that the ruler is horizontal. Place against forehead for added stability. Stand in front of a mirror, or ask someone else to measure for you.
- While looking straight ahead, measure the distance from the center of your right pupil to the center of your left pupil.
- Repeat a couple of times for accuracy and use an average for your final measurement.