Visual Acuity Converter
Snellen to Other Formats
Convert Snellen visual acuity to LogMAR, decimal, and MAR
LogMAR to Other Formats
Convert LogMAR visual acuity to Snellen, decimal, and MAR
Decimal Acuity Converter
Convert decimal visual acuity to Snellen and LogMAR
Formula
LogMAR = log10(Snellen denominator / 20) | Decimal = 20 / Snellen denominator | MAR = 10^LogMAR | Snellen = 20 / (10^(-LogMAR)) | LogMAR 0.0 = 20/20 = Decimal 1.0
Frequently Asked Questions
What does 20/20 vision mean?
20/20 means you can see at 20 feet what a person with normal vision sees at 20 feet. It is the baseline for normal visual acuity, not 'perfect' vision. Some people have 20/15 or 20/10 vision, which is better than the baseline.
What is legal blindness?
In the US, legal blindness is defined as best-corrected visual acuity of 20/200 or worse in the better eye, or a visual field of 20 degrees or less. This corresponds to a decimal acuity of 0.1 or LogMAR 1.0.
What is LogMAR and why is it used?
LogMAR (Logarithm of the Minimum Angle of Resolution) is a scientific scale for measuring visual acuity. It is preferred in research because it provides a linear, evenly-spaced scale (each 0.1 step = one chart line), making it suitable for statistical analysis unlike the Snellen fraction.
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