1. Mirror Method (DIY)
What You’ll Need: A mirror and a millimeter ruler
- Stand about 8 inches from a mirror in good lighting.
- Close your right eye and align the 0 mm mark of the ruler with the center of your left pupil.
- Switch eyes — close your left eye and open your right — and note the measurement at the center of your right pupil.
- That number is your pupillary distance.
Tip: If lining up the pupils is difficult, you can measure from the outer edge of one iris to the inner edge of the other.
2. With a Friend’s Help
What You’ll Need: A friend and a millimeter ruler
- Focus on an object 10–20 feet away, keeping your head still and eyes steady.
- Ask your friend to line up the 0 mm mark of the ruler with the center of one pupil.
- Then have them measure across to the center of the other pupil.
- Record that number — that’s your PD.
Note: This method tends to be more accurate than doing it solo.