Text Size and Weight
When designing an inclusive app, keep text size, weight, and layout in mind for clarity and readability. To learn how color and contrast can affect the legibility of text in your app, see Color and Contrast.
Use Dynamic Type and test that your app's layout adapts to all accessibility font sizes. Dynamic Type lets people pick the font size that works for them. Verify that your design can scale and is legible at all accessibility font sizes for both text and glyphs. (For sizes, see Larger Accessibility Type Sizes.)
As font size increases, avoid truncating text. It's best when people can simply scroll to see the same amount of text that's visible at the default font size. Don't truncate text unless people can open a separate view to read the rest of the content.
Increase the size of meaningful glyphs as font size increases. If you use glyphs to communicate important information, make sure the glyphs are easy to view at larger font sizes, too.
Maintain a consistent information hierarchy regardless of the user’s font size choice. For example, keep primary elements towards the top of the screen even when the font size is very large, so that people don’t lose track of these elements.
Use regular or heavy font weights in your app. Use Regular, Medium, Semi-Bold, or Bold font weights, because they are easier to see. Avoid UltraLight, Thin, and Light font weights, which can be more difficult to see.
Ensure that your app responds correctly and looks good when users enable bold text. People turn on the bold text accessibility setting to make text and glyphs easier to see. In response, your app should make all text bolder and give all glyphs an increased stroke weight.
Make sure custom fonts are legible. Custom typefaces can sometimes be difficult to read. Unless your app has a compelling need for a custom font, such as for branding purposes or to create an immersive gaming experience, it’s usually best to use the system fonts. If you do use a custom font, make sure it’s easy to read, even at small sizes.
Avoid full text justification. The whitespace created by fully justified text can create patterns that make it difficult for many people to read and focus on the text. Left justification (or right justification in right-to-left languages) provides a framing reference for people with learning and literacy challenges, such as dyslexia.
Avoid using italics or all caps for long passages of text. Italics and all caps are great for occasional emphasis, but overuse of these styles makes text hard to read.