The font size that is readable from 10 feet away largely depends on the type of font used and the viewer's vision, but as a general rule in event planning, we often use the 1:10 ratio. This means for every 1 inch of text, it can be seen from 10 feet away. Therefore, if you want your text to be readable from 10 feet away, you should consider using a font size of 1 inch or larger. However, it's essential to note that factors such as color contrast, lighting, and the complexity of the font can also affect readability. For optimal readability, choose a clean, simple font and high contrast colors.