What size should your sign, banner or vehicle graphics be? The following charts help Sign-Ups’ customers on how to create eye-catching van signage, banners and signs. Using custom signs is a great way to attract and connect with new clients and customers. When designing window signs, banners, or car signs, make sure your target market can read what you want to tell them. The size of the letters and logos, as well as the colors you choose, are crucial in creating a visible, easy-to-read sign.