Pupillary distance is measured in millimeters from the center of one pupil to the center of another pupil. This measurement helps to ensure that your prescription is properly centered in the spectacle lens for the clearest and most accurate vision.

PD represents the pupillary distance, which is measured from the right pupil to the left pupil. The PD of the adult is between 54-74. The children are between 43-54.

Pupillary distance can be expressed in two ways:

A: Single PD is the total distance between your pupils. such as 63mm.

B: Dual PD is the distance from your nose to the pupil next to you. The Dual PD measurement will be two numbers. such as left pd 31mm, right pd 32mm.

No PD measurement? You can contact your optometrist or make your own measurements or Find a friend to help measure more convenient and accurate than yourself

When purchasing a pair of glasses, it is important to have all the prescription details, and the preparation of the PD is very important in the process of buying the glasses.

Let's take a look at how to friend measure the Pupillary distance for you.

Step 1: Find a friend and a ruler.

Step 2: Your friend place the ruler on the bridge of your nose and use the ruler's 0 line to align the center of the left pupil.

Step 3: Measure the middle of your right pupil and still look into the distance. The distance between the left and right pupils is your PD. The distance between the middle of the nose and the left of the nose bridge is the left pupillary distance. The distance between the middle of the nose bridge and the right eye is the distance of pupillary distance. 

Some people are the same pd, showing a figure such as 63mm, each side is 31.5mm and some people are not the same as the left 31mm to the right 32mm. Left and right different interpupillary distance (dual pd) please refer to the article

Step 4: Repeat these steps 2 to 3 times to get consistent numbers.

Measure by yourself

Step 1: Stand 8 inches away from the mirror.

Step 2: Hold a ruler against your nose.

Step 3: Close your right eye and align the 0 mm ruler with the center of the left pupil.

Step 4: Look straight, then close your left eye and open your right eye.

Step 5: The millimeter line arranged in the center of the right pupil is your PD.

Step 6: Repeat these steps 2 to 3 times to get consistent numbers.