How to Figure an Eye Prescription for Computer Glasses

As people age, especially after the age of 40, the ability to see items up close often becomes more difficult. This is a condition that occurs naturally called presbyopia. It is because of this condition that people begin to find they have a need for glasses in order to work comfortably on the computer. If you find yourself in this category, then the idea of selecting which glasses to use may seem overwhelming. By following a few simple steps, you should be able to identify which strength of glasses will allow you to once again work on the computer comfortably and without eye strain 1.**


Measure the distance from your screen to your face. Distance is important, as it will take a different power for people who sit farther back from the screen.

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Look at the glasses prescription written by your eye doctor for everyday distance vision. The numbers you need are the numbers written for the sphere. An example of a prescription would be: +1.00 – 0.50 X 105. In this example, the sphere is the +1.00.

Calculate your glasses prescription for the computer 1.** If your computer screen is 21 to 35 inches away from you, you will want to add approximately 1.00 diopters to your prescription. For example: your prescription (for every day distance vision) is + 1.00 sphere. You will add 1.00 to it and the reading glasses prescription would then equal +2.00.

If your computer screen is 35 inches, or farther, away from you, you will need to add 1.50 diopters to your prescription. Using the same example of a distance prescription of +1.00, the computer prescription would be +2.50.

If you do not currently need glasses for distance, then start your calculations at zero; so continuing with the example, the computer glasses would be a +1.00.

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Record the calculations on a sheet of paper to take with you to the store.

Find a pair of glasses. The simplest way to find and buy a pair of computer glasses is to go to your local pharmacy 1.** Pharmacies typically have a display of several different glasses of varied strengths. You can locate the power of the glasses on the inside of the arm of the glasses if it is not clearly marked on the front of the lenses or on the packaging.

Try on a few pairs of glasses. If you measured your computer screen to be approximately 21 inches from where you sit, which is the general distance of most computers, then this is also the approximate length of your arm. Stand an arms length away from the reading chart provided by the glasses display and see if you can read print the approximate size of the text on your computer screen 1.

Fine-tune your glasses strength. If you feel it is not quite right, try going up or down with the power of the glasses by a quarter step (+/- 0.25) to see if you can find that perfect balance.


If after following the above steps you find that you are still not happy with your vision when working on the computer, it may be time to revisit your eye doctor. If needed, have a pair of glasses professionally made.

If you are concerned about being able to figure the correct strength yourself, there are many sites on the Internet that allow you to print out an eye chart and show you which strength may help depending on which line you have trouble reading. Simply search for "Computer Strength Eye Chart."

  • Measure the distance from your screen to your face.
  • If your computer screen is 35 inches, or farther, away from you, you will need to add 1.50 diopters to your prescription.
  • Try on a few pairs of glasses.