The industry recommended minimum reading time for a sign message is 5 seconds.

The chart on the right will give you a starting point for letter size, based on the speed limit of the nearest road. Traffic lights, stop signs, and other conditions may justify smaller character heights. Others such as visual obstructions, competing signage, and distance from the road may require larger character heights.

We have compiled this changeable letter guide to help you determine what letter size to use and then see an example under normal conditions. If you are undecided between two sizes, we recommend choosing the larger of the two. We can also advise you if special conditions or regulations exist.

Instructions

• Print out the letter examples, making sure to change "page scaling" to "none" in your print options so that the sample letters are printed at the correct size.
• Place the pages perpendicular to the road where your new sign will be located. It may be held, tacked to a wooden stake or pole, or taped to an existing sign.
• Drive by the letter chart at the normal traffic speed to get an idea of the readability of each letter size.