The font-display property in CSS controls how custom fonts behave while loading, impacting text visibility and user experience. It prevents issues like FOIT or FOUT by dictating whether fallback fonts are used and when the custom font swaps in. The common values include auto, block, swap, fallback, and optional, each offering different trade-offs between performance and design consistency. To use it, add font-display inside the @font-face rule with a chosen value like swap or fallback. When choosing a value, prioritize swap for always-visible text, fallback for faster rendering with a preference for custom fonts, and avoid block unless intentional invisibility is acceptable. Testing is key to finding the best option for your site's performance and aesthetics.
When you're working with web fonts, especially via @font-face, the font-display property plays a key role in how and when your custom fonts appear on the page. It controls how text is rendered while the font is loading — which can make a big difference in perceived performance and user experience.
Here’s what you need to know about font-display.
What does font-display do?
The font-display property determines how a custom font behaves while it's being downloaded. Without it, browsers may hide the text until the font loads (which can cause FOIT — Flash of Invisible Text), or show a fallback font first and then swap (FOUT — Flash of Unstyled Text).
By setting font-display, you tell the browser how long to wait for the font before showing a fallback, or whether to show text immediately using a system font and swap later.
Common values of font-display
You’ll typically use one of these five values:
- auto: The browser decides the behavior — often results in a short block period followed by a swap.
- block: The text remains invisible for a short time while waiting for the font to load.
- swap: A fallback font shows immediately, and the custom font swaps in once it's ready.
- fallback: A short block period (like 100ms) and a short swap period — balances between loading speed and design consistency.
- optional: The browser might not even bother loading the font if it thinks it will delay rendering too much.
If you're aiming for a good balance between aesthetics and performance, swap or fallback are usually your best bets.
How to use it in CSS
You apply font-display inside your @font-face rule like this:
@font-face {
font-family: 'MyCustomFont';
src: url('myfont.woff2') format('woff2');
font-weight: 400;
font-style: normal;
font-display: swap; /* This is where the magic happens */
}Just pick the value that fits your needs and add it into each @font-face declaration. No extra JavaScript needed — it just works as part of standard CSS.
When to use which value?
Choosing the right value depends on your site's priorities:
- Use
swapif you want text always visible and don’t mind a brief switch from fallback to custom font. - Go with
fallbackif you want fast rendering but still prefer the custom font when possible. - Stick with
autoonly if you’re okay with the browser making the decision — but be aware it might vary across browsers. - Avoid
blockunless you have a specific reason and are okay with some invisible text during load. - Use
optionalcarefully — it's great for low-priority fonts but could result in missing fonts on slow connections.
Each has trade-offs, so test them out and see how they affect your actual page load experience.
That’s basically it. It’s not complicated, but it can have a real impact on how fast your content feels to users.
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