UPDATE: This feature is pulled from the core in favour of developing it as a canonical plugin.

Without you knowing.

WordPress 6.1 will add a little controversial feature of generating a WebP image by default for every uploaded JPEG image. WebP image upload support was added in WordPress 5.8 for the single-site installations and you still need to use code-snippets or plugins to add WebP images in multi-site WordPress installations.

Now, since WordPress 6.1, WebP images will be used by default for your website content. If the proposal goes as planned.

Personally, I like this feature because WebP images have a lot of benefits over traditional JPEG and PNG formats. One notable benefit is it’s blazingly fast and small in size. Pagespeed insights also recommend using the ‘next generation image formats’ like WebP.


Many people expressed disagreement on this feature especially since it’s no opt-in and has no option to opt-out without code. Some of the points I’ve extracted from various resources:

1) You didn’t know the WebP format is being generated and used on your site, even though you wanted the JPEG format. It’s no more your decision to choose the image format, WordPress decides for you.

2) You’ll need a code snippet or yet another plugin to disable this feature, there’s no default option. They blame the Decisions, not Options WordPress Philosophy.

3) Delay in image uploads compared to the usual time.

4) Some web hosts tend to disable WebP as a policy decision because it’s too CPU-intensive on shared servers.

5) Disk Space. Image files being re-generated means more disk space than usual.

6) Increase in hosting cost. Your bill will rise. Seriously, if your site is dependent on lots of image uploads.

7) Not all browsers, email clients, RSS clients, Smart TVs, etc. support WebP images yet.

8) WebP images are not always smaller than JPEG.

9) Possible conflicts with Lazy Loading.

10) WebP does not allow the easy download of images from their site.

11) Re-generating thumbnail will affect your existing images as well. If you have a huge number of images (let’s say 50k), 50k more will be re-generated on your site, causing a disk-space issue. Just a reminder, regenerating thumbnail happens automatically in conditions such as changing theme, plugins, etc. So, you can say all the existing sites/images will be impacted seriously by this feature.

12) The performance benefits of WebP are minimal over the optimized JPEG image.

Disable WebP by default

This feature to enable WebP by default can be disabled by a simple code-snippet though.

add_filter( 'wp_upload_image_mime_transforms', '__return_empty_array' );

The code snippets can be added in your theme’s (preferably child theme’s) functions.php. Here’s how to easily add custom code snippets in your site.


Photo from canva.com, expressing frustration

WordPress 6.1 uses WebP images for your site content by default
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Sanjeev Aryal

Don't bury your thoughts, put your vision into reality ~ Bob Marley.

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