Glasses prescription reader

About this calculator

Copy the numbers from your glasses prescription and get a plain-language explanation of each one for each eye, your spherical equivalent, the near-vision prescription when there is an ADD, and the same prescription written in the opposite cylinder form.

What you need

• Your glasses prescription: SPH, and CYL, AXIS and ADD if they are filled in
• Your PD (pupillary distance), if it is on the prescription

How it is calculated

Spherical equivalent = sphere + cylinder ÷ 2. The other cylinder form is sphere + cylinder, the cylinder with its sign reversed, and the axis turned 90°. The near-vision sphere is sphere + ADD. Myopia ranges follow the International Myopia Institute: myopia at −0.50 D or more minus power, high myopia at −6.00 D or more.

What the result can and cannot tell you

A prescription is the lens power your eyes need, not a measure of how well you see. People with the same prescription can see differently, so vision (like 20/40) is measured separately on a chart. Myopia ranges follow the International Myopia Institute definitions.

References

1. International Myopia Institute: Defining and classifying myopia. IOVS 2019
2. Netra Eye Institute: Myopia
3. Netra Eye Institute: Astigmatism

Related

• Visual acuity converter
• Glasses to contact lens converter
• Reading glasses strength estimator
• Myopia guide
• All eye calculators

For information only. These tools explain numbers and do not replace an eye examination or your eye doctor’s advice. Values you enter stay in your browser.