Visual Acuity
Calculate Visual Acuity instantly with the exact formula and a worked example.
Visual Acuity
Distance to the chartm
Standard distance D of the last line read (printed on the chart)m
Visual acuity (1.0 = normal)
0.5
logMAR
0.3
Snellen (20 ft)
20/40
Snellen (6 m)
6/12
Assessment
Reduced, no visual impairment per WHO (≥ 0.5)
More about: Visual Acuity
What it calculates
The “Visual Acuity” calculator computes Visual acuity (1.0 = normal) from 2 parameters: distance to the chart (m), standard distance d of the last line read (printed on the chart) (m).
A standard physics formula used in educational and engineering tasks.
Example calculation
With parameters Distance to the chart = 5 m, Standard distance D of the last line read (printed on the chart) = 10 m the result is 0.5.
How to use
- Enter distance to the chart and standard distance d of the last line read (printed on the chart) — each field above is adjustable with a slider.
- Visual acuity (1.0 = normal) is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is Visual Acuity calculated?
The Visual Acuity calculator computes Visual acuity (1.0 = normal) from distance to the chart, standard distance d of the last line read (printed on the chart). Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the Visual Acuity calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.
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