Astigmatism to Normal Prescription Converter Calculator for Contact Lenses

For all those who occasionally wish to wear contacts but do not want to purchase expensive Toric lenses can try using our free Astigmatism to Normal Prescription Converter Calculator. You can also use the conversion chart if you find that easier.

This calculator converts your eyeglasses prescription to contact lens prescription. Although they are almost always the same, the prescription will be slightly different if you have a mild case of astigmatism. To learn more about astigmatism and contact lenses, checkout this article. There also a how bad is my eye prescription calculator you might want to check out.

Astigmatism to Normal Prescription Converter Calculator

A simple script has been prepared for you so that you can simple plug and chug your prescription values and get your astigmatism contact equivalent. All you need are the eye prescription numbers of your

  • spherical
  • cylinder
  • axis

In fact, you don’t even need your axis number for this.

The calculator below is based on the formulas presented in this article.

Be sure to use the correct signs in each box. For example, if your Spherical value is -3.00, make sure you type in the minus sign. Same goes for the Cylinder value as these can also be positive or negative depending on what the optometrist gave you.

Note that the Regular Contact Lens number is reported to the nearest 0.25 decimal place, as contact lenses are available in the market with increments of 0.25.

Always consult a medical professional before following stuff you find on the internet.

Spherical :


Your Regular Contact Lens Value is

Make sure to double check the results with an optometrist. Some opticians suggest that since contacts are closer to the eyes than glasses, it is okay to use weaker powered lenses, while completely ignoring the cylinder value.

If your cylinder value is above 0.5, then you should never ignore it. Also, since this Converter gives a makeshift solution for those with Astigmatism, try to not rely on its results for long term usage and go get yourself some Toric contacts.

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convert astigmatism to regular contacts prescription