We always recommend you get your PD from your eye doctor, or your optician, however, if you are unable to acquire this professionally, please follow the following steps for measuring your pupillary distance (PD) measurement.
Put on a pair of eyeglasses, and focus on an object about 20 feet away directly in front of you. Have a felt marker ready!
Mark your right lens and your left lens with the felt marker directly in front of your pupils as you gaze at the distant object.
Measure the distance between the two dots with a millimeter ruler. You have your PD.
**Note: for near vision lenses, focus on a reading object, or a computer screen directly in front of you for a Near PD.