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 font sizes. Dynamic Type lets people pick the font size that works for them. Verify that your design can scale and that both text and glyphs are legible at all font sizes. On iPhone or iPad, for example, turn on Larger Accessibility Text Sizes in Settings > Accessibility > Display & Text Size > Larger Text, and make sure your app remains comfortably readable. You can download the Dynamic Type size tables in the Sketch, Photoshop, and Adobe XD Apple Design Resources for each platform.
As font size increases, keep text truncation to a minimum. In general, aim to display as much useful text in the largest accessibility font size as you do in the largest standard font size. Avoid truncating text in scrollable regions unless people can open a separate view to read the rest of the content. You can prevent text truncation in a label by configuring it to use as many lines as needed to display a useful amount of text; for developer guidance, see numberOfLines.
Consider adjusting layout at large font sizes. When font size increases, inline items and container boundaries can crowd text, making it less readable. For example, if you display text inline with secondary items — such as glyphs or timestamps — the text has less horizontal space. At large font sizes, an inline layout might cause text to truncate or result in overlapping text and secondary items. In this case, consider using a stacked layout where the text appears above the secondary items. Similarly, multiple columns of text can become less readable at large font sizes because each column constrains horizontal space. In this case, consider reducing the number of columns when font size increases to avoid text truncation and improve overall readability. For developer guidance, see isAccessibilityCategory.
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. When you use SF Symbols, you get glyphs that scale automatically with Dynamic Type size changes.
Maintain a consistent information hierarchy regardless of the current font size. For example, keep primary elements toward 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 people 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. The system fonts and SF symbols automatically adjust to the bold text accessibility setting.
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.