How To Design A Sign: How Big Should Your Letters Be?

When it comes to choosing sizes, most people seem a bit lost. They don't know how to go about it mathematically, so they take their best guess and hope the sign will turn out okay.

However, hope is not a strategy.

Here's a strategy you can use right now to properly size your new signage: Think backward.

That's right. If you want to size your new signage properly, it should be "reverse engineered." Don't worry, it's easy to do, once you learn this simple secret.

The secret is to size your letters first before you size your sign.

After all, people don't read signs. They read the words displayed on signs. But only if the words are easy enough to read at a glance. If the letters are too small or too difficult to read, most people just won't bother.

So focus on choosing the size of your lettering, first. And then fit the sign to the size of the letters.

Which factors determine how big the letters should be?

There are two primary factors that determine what size the letters should be. Of course, there are important secondary factors to consider too. And you'll have the opportunity to learn about those in our advanced guide.

The two primary factors for determining letter size are: Distance and Speed (for signs to be viewed by passing motorists).

First, you need to know the viewing distance.

The viewing distance equals how far away you want your sign to be readable. Yes, I know it may take you a few minutes to determine the distance. But guessing is outright gambling. And there's no point in taking an unnecessary risk and having a sign that can’t be read by motorists.

Once you know the distance, we have a Letter Sizing Calculator you can use.

This Letter Sizing Calculator is based on a joint research project regarding letter visibility by The Pennsylvania Transportation Institute, Penn State University, and the United States Sign Council (USSC)

There's no need to guess at sizes anymore. The Letter Sizing Calculator simplifies the math for you.

Here's an example. Let's suppose you need a new sign for your business. And you are going to be placing this sign directly on the building. How far away do you want potential clients to be able to read your message?

For this example, let's assume you need the sign to be readable from at least 60 feet away. The Letter Sizing Calculator will automatically show you 2 sizes:

The minimum size the letters have to be to be readable
Plus the recommended size for optimal visibility.

In this case, the minimum readable size is a 3" tall letter, and the size recommended for optimal visibility is a 6" tall letter. (For added advertising impact, businesses often go even larger.)

How do you use this letter size information to design your sign?

For the main text, consider using the size recommended for easy readability. (Or larger). And then you can go as low as the smallest size recommended for the rest. It's all according to the purpose of the sign and what you want it to look like.

The illustration below simulates the readability of specific size characters from between 100 to 400 feet away. Compare the readability of each size letter at the various distances.

Viewed 100 Feet Away:

Letter Sizing and 100 feet Distance