Content

• To step
• Method 1 of 3: Measure your pupil distance yourself
• Method 2 of 3: Have someone else measure your PD
• Method 3 of 3: Have your PD measured by an ophthalmologist
• Tips
• Warnings

Pupil distance (PD) is the distance between your pupils, measured in millimeters. Ophthalmologists always measure this distance to make sure prescription glasses fit properly. The average PD in adults is 62 millimeters, although the normal range for most people is between 54 and 74 millimeters. You can measure your PD yourself at home or ask someone to help you, or you can have it professionally done by an ophthalmologist.

To step

Method 1 of 3: Measure your pupil distance yourself

1. Use a ruler with millimeter units. To measure your PD at home, you need a ruler with millimeter markings. If you don't have a ruler at home, you can print a PD measuring ruler online from many facial center and eyewear retailer websites. When you print the page, make sure that you set your printer so that it doesn't scale the image.
   • Some online eyewear stores use programs that allow you to photograph yourself with a credit card against your face in front of the scale, but most require you to measure the distance manually.
2. Stand in front of a mirror. If you measure your own PD, you must use a mirror. Make sure you are in a well-lit area so you can line up the ruler and see the ruler's marks. To get a good reading, you need to stand about 20 centimeters from the mirror.
   • Hold the ruler directly over your eyes, straight over your eyebrows.
   • Keep your head upright to ensure proper measurement.
3. Close your right eye to center your left pupil. It is easiest to measure one eye at a time by closing the other eye. Start by closing your right eye and keep the zero millimeter mark exactly above the center of your left pupil. Try to get an exact zero alignment as this is important for the correct reading of your measurement.
4. Read and measure the distance to your right pupil. Without moving your head or the ruler, open your right eye and find the exact millimeter mark that falls on your right pupil. Make sure to look straight ahead in the mirror to ensure an accurate reading. The number (in millimeters) that corresponds to the center of your pupil, or as close to the center as you can measure, is your PD.
   • It is best to re-measure your PD three or four times to make sure your reading is as accurate as possible.

Method 2 of 3: Have someone else measure your PD

1. Stand close to the other and look at each other. You should be about 8 inches from the other, just like you would if you were measuring your PD in front of the mirror. Do not stand too close or too far away to ensure an accurate measurement.
2. Look above the person's head. Unlike measuring your own PD in the mirror (where you can't avoid looking at your own reflection), having someone else measure your PD requires you to look past that person. Have the other person squat or sit in front of you so that they are out of sight, and stare at something in the distance about 10 to 20 meters away.
3. Have the other person take the measurements. You have to keep your eyes perfectly still while the other person measures your PD. He or she should align the ruler the same way you would in the mirror on yourself. The person should align the zero mark with the center of one pupil and measure where the center of your other pupil falls.

Method 3 of 3: Have your PD measured by an ophthalmologist

1. Make an appointment with your eye doctor. You usually have to make an appointment to have your PD measured by an ophthalmologist. While you are there, your eye doctor will likely want to test your eyesight to make sure your current prescription is still correct. This may include testing your eye muscles, visual acuity, field of vision, as well as a refraction and retinal exam.
   • If you don't already have an eye doctor, you can find one in your area by searching online or checking your local phone book.
   • If you have had your eyesight tested in the past year, you do not need a new eye test. The eye doctor who performed your eye test may also have your PD in your chart from the previous exam.
2. Have your pupil size measured. Depending on the tests you have undergone, your eye doctor may want to check the size of your pupils using a digital pupil gauge. The ophthalmologist can also use an eyepiece measuring device. Both handheld devices can measure the size of your pupil and the distance between your pupils.
   • A pupil meter looks like a pair of large binoculars, and you just have to look through the lenses while your doctor takes the measurements.
   • An eyepiece measuring device can look like a digital camera, depending on the make and model your doctor uses.
3. Ask for a prescription and your PD. The advantage of having your PD measured by an ophthalmologist is that you leave with both an accurate reading and a valid prescription for your next pair of glasses. Many online retailers need your PD and a prescription to be able to sell you glasses, so an up-to-date eye exam will simplify the process and ensure you get the right prescription for your eyes.

Tips

• The pupils are sometimes difficult to see, especially if you have dark irises. Good lighting will help you see the pupil better and get a more accurate reading.

Warnings

• Do not poke your eyes. If someone else is helping you measure, make sure they are very careful around your eyes.