Visual Acuity Converter

Convert between Snellen fraction, LogMAR, decimal acuity, and MAR notation for visual acuity measurements.

Snellen Numerator

Snellen Denominator

Decimal Acuity

LogMAR

MAR (Min Angle of Resolution)

1 arcmin

Metric Snellen (6/x)

6/6

How to Use This Calculator

Enter the Snellen Numerator — the test distance in feet (typically 20 for US charts, 6 for metric).
Enter the Snellen Denominator — the smallest line the patient reads (e.g., 20 for 20/20, 40 for 20/40).
The calculator instantly converts to Decimal Acuity, LogMAR, MAR (Minimum Angle of Resolution), and the metric 6/x equivalent.
LogMAR 0.0 = 20/20 (normal); positive LogMAR values indicate reduced acuity.
Use these conversions when comparing results across clinical studies, visual acuity charts, or international records.

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Formula

LogMAR = log₁₀(denominator / numerator)

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