The WebP image format was introduced in WordPress 5.8 version that was released in July 2021. Since then, you can upload and use images in the WebP format, just like JPEG.
Now, the performance team has published a proposal stating that WebP images will become the default format to expand core support for this image format in the near future. If this proposal is approved, WordPress 6.0 will use WebP images by default for content and generate them by default for new JPEG uploads.
According to WordPress Core Contributor Adam Silverstein, “WebP was developed as a modern image format that provides superior compression on the web. Images are often some of the largest resources used by websites, and using WebP creates websites that are lighter and faster. Compared to JPEG images, WebP images generated by WordPress are almost always smaller, with a 30% file size reduction on average.”
Once WebP becomes the default format on WP websites, users will not experience any difference in their usual upload flow. WordPress would automatically convert images into the default version. According to research from Can I Use, WebP is supported by over 94% of web browsers. A few browsers like a version of Safari on macOS, Internet Explorer 11, and KaiOS Browser don’t support this image version.
Regardless of the benefits of the performance of this image format, several contributors have expressed concern about social platforms and email clients not supporting WebP.
“I feel like WebP is not yet ready to become a ‘hardcoded default’ in the post_content due to all the reasons mentioned in the previous comments,” Kaspars Dambis said. “Many web clients (which are not just browsers) don’t support WebP formats — RSS clients, email clients, smart TVs, eBook readers, open graph parsers, desktop image viewers, etc. These are all important users of the web.”
In response to this statement, Silverstein answered, “One important note about what this feature doesn’t change: JPEG sub sizes are still generated and stored in the same meta fields,” he said. “For that reason, consumers of RSS feeds or REST media endpoints or OG tags, for example, will continue to use the JPEG sub sized versions.”
If you want to test WebP images on your website, then install the Performance Lab Plugin with the “WebP Uploads” module activated. The Performance Team encourages developers and content created to test and share their feedback. We’ll have to wait to find out if WebP becomes default in WordPress 6.0 or not.