Sign Letter Height Calculator

Use our simple Sign Letter Height Calculator to determine the exact size of letters or symbols you will need for your sign in order for it to be read and understood.

Simply enter the posted maximum speed for the location of your sign and the number of letters and symbols to be displayed.

The calculator will let you know the minimum letter height you should have for simple, complex, and multi-lane driving conditions.

How Our Sign Letter Calculator Works

You can determine the perfect height for letters and symbols for your signage by doing the following:

Step 1: Enter the posted maximum speed for the location of your sign in Km per hour.

Step 2: Enter the number of letters and symbols on your sign.

Step 3: The calculator will display your minimum letter height for your sign for 3 different types of driving environments:

• Simple: Simple driving environment.

• Complex Driving Environment:  Developed town or city commercial areas. Single or multi-lane travel under 35 mph (56 Km/h)

• Multi Lane: Developed urban/suburban commercial areas. Multi-lane travel over 35 mph (56 Km/h)

Step 4: The calculator will display the viewer reaction distance.

Viewer Reaction Distance is the distance a driver needs to see your sign, read it, and react safely while moving.

If a car is going faster, it covers more ground every second — so the sign needs to be readable from farther away.

So VRD basically tells you: How far away your sign must be readable so the driver doesn’t miss it.

Step 5 (Optional): Get a more accurate legibility index by matching your sign's parameters (text, colour & background) and choosing the corresponding legibility index from Chart A.

For more precise calculations, you can enter the legibility index from our handy chart (also included in the download) for the letter style, letter colour, and background colour for your sign.