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Calcimator

Sign Visibility Calculator

Calculate minimum and recommended letter heights for sign legibility at a given viewing distance and vehicle speed.

Inputs

Results

Min Letter Height

16.7 in

Recommended Height

20 in

Est. Sign Width10 ft
Reaction Dist (ft)198
How to Use This Calculator
  1. Enter the viewing distance (ft) and vehicle speed (mph).
  2. Review minimum and recommended letter height (in) for legibility at the given distance and speed.
  3. Check recommended sign width (ft) for the letter layout.
  4. Use the 1-inch-per-30-feet rule as a starting point: a sign read at 300 ft needs 10-inch letters minimum.
  5. High-contrast color combinations (dark on light, yellow on black) allow slightly smaller letter sizes.
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