Since signs are used in a number of different ways, there is no one-size-fits-all measurement for the “perfect” sign. For instance, a window display sign has a specific purpose that is not the same as a sign placed on the pavement to advertise a nearby business.
Consider the following:
Purpose — Take into consideration where and what you will be using a sign for. If it is only going to be for an in-store promotion, you can keep the font small and not worry about it being illegible. For a sign pointing the way to your store, you will want to make the text big enough to catch the eyes of pedestrians and drivers.
Positioning — Another factor worth considering in line with a sign’s purpose is its positioning. If you are placing a sign on the side of a street, positioning it perpendicular to the street will make it much easier to read for commuters and cars passing by. Since 35% of customers find out about a local business from seeing it while passing, then it’s all the more pertinent that your target audience knows your store is within the vicinity.
Font Size — The size of the font also plays a big role in making a sign legible. It puts a limit on how far away a sign can draw attention and be clearly understood. A sign that is placed above eye level can command attention more easily with big fonts, while a sign below eye level basically requires large text for people to notice it.
To help you choose the right font size that is appropriate for the signs you will be using, here is a handy table listing common letter heights, the distance where they make the most impact, and the furthest distance the average person can still read the sign: