Contact Lens Prescription Conversion Calculator

Contact Lens Conversion Calculator

Contact Lens Vertex Calculator

Want to quickly convert your glasses prescription to a contact lens prescription? This easy-to-use calculator provides an instant estimate for colored and circle lenses.

Right Eye (OD)

Required field (in diopters)

Leave blank if you don't have astigmatism

Only required if you have cylinder value for astigmatism

Left Eye (OS)

Required field (in diopters)

Leave blank if you don't have astigmatism

Only required if you have cylinder value for astigmatism

Important Notes:

  • This calculator provides an estimate using the vertex distance formula. Always consult with your eye care professional for accurate prescriptions.
  • Contact lens prescriptions require additional parameters like base curve and diameter that are not calculated here.
  • Results are rounded to the nearest 0.25 diopter for practical use.
  • For prescriptions with high cylinder values (>2.00D), professional fitting is essential.

Note: This calculator is an estimate (For information only, not a prescription) and does not replace a professional eye exam.

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FAQs

Q1: What is a contact lens conversion calculator?

A: Itโ€™s a tool that transforms your eyeglasses prescription (sphere, cylinder, and axis) into an estimated contact lens prescription using the vertex distance formula.

Q2: Why canโ€™t I use my glasses prescription directly for contacts?

A: Contact lenses sit directly on your eye (vertex distance zero), whereas glasses sit about 12 mm awayโ€”this distance affects effective lens power. The calculator corrects for that.

Q3: Is this tool accurate for toric (astigmatism) lenses?

A: Yes, it factors in cylinder and axis values. However, if your cylinder is over 2.00 D, a professional fitting is strongly recommended.ย 

Q4: Do colored or circle contact lens brands affect conversion?

A: No, power requirements stay the same across brands. But coverage differences like base curve and diameter may vary, so always choose the correct fit.ย 

Q5: Can I use this instead of visiting an optometrist?

A: No, this is only an estimation tool. A proper eye exam and lens fitting are essential for safety, comfort, and accurate prescription.ย 

Browse our Colored Contacts collection for stylish pairs suited to your prescription.