Your Glasses Prescription to Contact Lens Calculator
Convert your glasses prescription to the correct contact lens prescription in seconds with our accurate, free online calculator.
Prescription Calculator
Simply enter your glasses prescription details below to instantly get the equivalent contact lens prescription.
Why Use Our Calculator?
Accurate prescription conversion with tools designed by eye care professionals.
Precise Conversion
Takes into account vertex distance for accurate results
Our calculator uses scientifically validated formulas to ensure the most accurate conversion from glasses to contact lenses.
Toric Lens Support
Special calculations for astigmatism
Properly converts cylinder and axis values for toric lenses, ensuring clear vision for those with astigmatism.
Expert Information
Educational resources created by optometrists
All of our content is reviewed by licensed optometrists to ensure accuracy and provide you with the best information.
Prescription Calculator
Convert your glasses prescription to contact lenses with our free online tool.
Cost Estimator
Compare prices of different contact lens brands and types for your prescription.
What Users Say
Thousands of users trust our calculator for their contact lens prescriptions.
Sarah M.
Verified User
"This calculator saved me a trip to the optometrist! The conversion was spot on, and I was able to order my contact lenses online with confidence."
James K.
Verified User
"As someone with astigmatism, finding the right toric lens prescription was always challenging. This calculator made it simple and accurate."
Rachel L.
Verified User
"The educational resources helped me understand my prescription better. I now know exactly what all those numbers mean!"
Understanding Contact Lens Prescriptions
Converting your glasses prescription to a contact lens prescription isn't simply a matter of using the same numbers. Contact lenses sit directly on your eye, while glasses sit at a distance (the vertex distance), which affects the required prescription strength.
Types of Contact Lenses
- Daily disposablesSingle-use lenses that are discarded each day
- Monthly lensesReusable lenses that last approximately 30 days with proper care
- Toric lensesDesigned for people with astigmatism, with special markers to maintain proper orientation
- Multifocal lensesFor people who need different prescriptions for near and far vision
Key Differences
Vertex distance adjustment
The space between your eye and glasses affects the effective power
Tear film interaction
Contact lenses interact with your tear film, which can affect optical properties
Corneal shape
The curvature of your cornea affects how contact lenses fit and perform
Oxygen permeability
Different materials allow different amounts of oxygen to reach your eye
Our calculator uses established optical formulas to account for these differences, particularly the vertex distance adjustment which is most significant for stronger prescriptions.