2026 20/20 Vision Calculator

Estimate Snellen acuity, decimal acuity, and visual angle from test distance and smallest readable letter size.

1.0M uses Updated · 2026-05-25 Runs locally · zero upload
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How to Use the 2026 20/20 Vision Calculator

Enter test distance in meters or feet, then enter the height of the smallest readable optotype in millimeters or inches. Both inputs should refer to the same vision test.

The calculator estimates visual angle, decimal acuity, and an approximate Snellen value such as 20/20 or 20/40. Larger required letters generally produce a larger Snellen denominator.

Formula and Method - 2026 20/20 Vision Calculator

Decimal acuity = 5 ÷ letter visual angle in arcminutes

Standard 20/20 vision corresponds to a full optotype height of about 5 arcminutes, with stroke detail near 1 arcminute. The calculator estimates visual angle from letter height and distance, then converts it to decimal and Snellen-style acuity.

Use Cases for the 2026 20/20 Vision Calculator

  • Converting nonstandard distance tests into approximate 20/xx notation.
  • Comparing how distance and letter size change the acuity ratio.
  • Teaching the relationship between 20/20, decimal acuity, and visual angle.

Frequently asked questions about 2026 20/20 Vision Calculator

What does 20/40 mean?

A person sees at 20 feet what a typical 20/20 observer can see at about 40 feet.

Is letter height the stroke width?

No. Enter full optotype height; standard optotypes span about 5 arcminutes.

Can this replace an eye exam?

No. It is a geometric conversion tool, not a standardized clinical exam.