Convert your eyeglass prescription to the 20/20 visual acuity scale with our free eye prescription converter. This essential tool helps you understand your visual acuity by translating diopter measurements into the familiar 20/20 scale used by eye care professionals.
The convert to 20/20 scale calculator uses these standard measurements:
20/20: Normal vision (can see at 20 feet what should be seen at that distance)
20/40: Can see at 20 feet what normal vision sees at 40 feet
20/200: Legal blindness (without correction)
20/15: Better than average vision
20/10: Exceptional visual acuity
Diopter to 20/20 Conversion Chart
Our eye prescription to 20/20 calculator approximates these common conversions:
Nearsightedness (Myopia)
-0.50 D: ~20/40 vision
-1.00 D: ~20/50 vision
-2.00 D: ~20/100 vision
-3.00 D: ~20/200 vision
Farsightedness (Hyperopia)
+0.50 D: ~20/25 vision
+1.00 D: ~20/30 vision
+2.00 D: ~20/50 vision
+3.00 D: ~20/80 vision
Astigmatism Correction
The 20/20 vision calculator accounts for astigmatism by:
Combining sphere and cylinder: For total refractive error
Weighting cylinder value: 50% contribution to visual acuity
Considering axis: Direction of astigmatism correction
Special cases: High astigmatism (>3.00 D) requires professional assessment
Common Vision Questions
Our prescription to 20/20 converter helps answer these frequent questions:
"What does 20/40 vision mean?" (Can see at 20 feet what normal vision sees at 40 feet)
"How bad is my -2.50 prescription?" (~20/125 equivalent without correction)
"Can I get 20/20 vision with glasses?" (Most prescriptions can achieve 20/20 with proper correction)
"Is 20/15 vision possible?" (Yes, with exceptional natural vision or slight overcorrection)
Pro Tip: For the most accurate conversion, have your current prescription handy and enter all values (sphere, cylinder, and axis) from your latest eye exam.
Frequently Asked Questions
How accurate is this eye prescription calculator?
Our diopter to 20/20 calculator provides estimates within 5-10% of clinical measurements. Exact visual acuity can vary based on individual factors like pupil size and eye health.
Does this calculator work for contact lens prescriptions?
Yes, but contact lens prescriptions may differ slightly from glasses prescriptions, especially for higher powers. Use your glasses prescription for most accurate results.
Can I use this for children's prescriptions?
Yes, but children's visual systems are still developing. Always consult a pediatric optometrist for precise assessments.
How does age affect these calculations?
After age 40, presbyopia (difficulty focusing near) becomes a factor. Our calculator includes adjustments for reading prescriptions when selected.
Eye Care Resources
For professional eye care information:
American Optometric Association (https://www.aoa.org)
American Academy of Ophthalmology (https://www.aao.org)