WordPress 6.5 adds AVIF support 

WordPress 6.5 supports AVIF, a modern image format that offers significant improvements in image quality and compression over previous formats like JPEG, PNG, and even WebP.  AVIF images can be up to 50% smaller than JPEGs while maintaining the same image quality. AVIF images also support a wide range of colors (including HDR) and produce sharper images than JPEGs, especially in areas with high detail.

From WordPress version 6.5 forward, you can upload and use AVIF images in WordPress just like you would a JPEG or PNG image today – as long as your hosting environment supports AVIF. Switching to the AVIF format for your images is likely to improve your site’s performance and your site visitor’s experience. 

How AVIF helps you

AVIF images are significantly smaller than their JPEG equivalents, so pages load more quickly and take less bandwidth to transmit. AVIF images still get all of the benefits of the responsive images, Fetch Priority, and lazy loading that WordPress supports by default. Finally, AVIFs are supported in all major browsers, so most sites can start using them today.

Creating AVIF images

Many image editing tools support exporting to AVIF. You can also use command line conversion tools or web based open sourceOpen Source Open Source denotes software for which the original source code is made freely available and may be redistributed and modified. Open Source **must be** delivered via a licensing model, see GPL. tools like Squoosh. Once you save your images as AVIF, upload them to WordPress and use them like you would any other image. WordPress can also create AVIFs for you automatically, for more details, see the FAQ item below.

Using AVIF images in WordPress

AVIF images work like any other image format in WordPress, with a few important notes:

AVIF in WordPress depends on support in your web server’s image processing library (WordPress has built-in support for both Imagick and LibGD for image processing). You can check for AVIF support in wp-adminadmin (and super admin) by visiting Tools -> Site Health, clicking the “Info” tab and expanding the “Media Handling” section, then finally looking for “AVIF” in the list of supported formats.

If your audience includes a significant number of users on an unsupported browser, either avoid using AVIF images, or enqueue a browser polyfill.

FAQ

Q: How do I adjust the compression level used for generated AVIF images?

The wp_editor_set_quality filterFilter Filters are one of the two types of Hooks https://codex.wordpress.org/Plugin_API/Hooks. They provide a way for functions to modify data of other functions. They are the counterpart to Actions. Unlike Actions, filters are meant to work in an isolated manner, and should never have side effects such as affecting global variables and output. can be used to set the quality setting. The passed mime type enables setting by type, for example:

// Use a quality setting of 75 for AVIF images.
function filter_avif_quality( $quality, $mime_type ) {
	if ( 'image/avif' === $mime_type ) {
		return 75;
	}
	return $quality;
}
add_filter( 'wp_editor_set_quality', 'filter_avif_quality', 10, 2 );

How can I output lossless AVIF images?

Using a compression level of 100 will set AVIF to its lossless mode.

Q: Can WordPress create AVIF images when I upload JPEGs?

Yes. Developers can use the image_editor_output_format filter to specify this type of transformation for uploads. Here is an example:

// Output AVIFs for uploaded JPEGs
function filter_image_editor_output_format( $formats ) {
	$formats['image/jpeg'] = 'image/avif';
	return $formats;
}
add_filter( 'image_editor_output_format', 'filter_image_editor_output_format' );

If I use WordPress multisitemultisite Used to describe a WordPress installation with a network of multiple blogs, grouped by sites. This installation type has shared users tables, and creates separate database tables for each blog (wp_posts becomes wp_0_posts). See also network, blog, site, will all my sites work with AVIF images?

No. Multisite stores the file types that users are allowed to upload when a site is created. We are still working on improving this in #53167. In the meantime, to ensure all existing sites on a networknetwork (versus site, blog) allow AVIF files, you can use the site_option filter in a network mu-pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party to add avif to the allowed file types for all network sites:

// Ensure all network sites include AVIF support.
function filter_site_option_upload_filetypes( $filetypes ) {
	$filetypes = explode( ' ', $filetypes );
	if ( ! in_array( 'avif', $filetypes, true ) ) {
		$filetypes[] = 'avif';
	}
	return implode( ' ', $filetypes );
}
add_filter( 'site_option_upload_filetypes', 'filter_site_option_upload_filetypes' );

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Thanks to @stevenlinx and @westonruter for reviewing this post.

#6-5, #core-images, #dev-notes, #dev-notes-6-5, #images