How big should my text be to read a banner or sign from a distance?
Signs & Banners
It depends on how far away people will be. A common rule of thumb: every inch of letter height gives you about 10 feet of easy reading distance. For a sign people will see from 50 feet away, plan on letters at least 5" tall.
Bold, simple fonts read better from far away than thin or script fonts, and strong contrast between the text and the background matters as much as size. Keep the message short. People driving or walking by get a few seconds, not a paragraph.