How to measure your PD
Your pupillary distance (PD) is the millimeter gap between your pupils. It centers your prescription correctly in each lens.
Method 1 — with a friend
Hold a millimeter ruler flat against your brow. Look straight ahead at a wall 3 meters away. Have your friend measure from the center of your left pupil to the center of your right pupil. Repeat 3 times and average.
Method 2 — solo with a mirror
Hold the ruler against your brow, look at your own reflection from arm’s length, and align 0mm with the center of your right pupil. Read across to the center of your left pupil.
Typical ranges
Adults: 54–74mm. Children: 41–55mm. Don’t worry about being off by 1mm — most prescriptions tolerate it.