What is WebP?
The WebP image format is a next-gen format developed primarily by Google as a replacement for JPG, PNG, and GIF. WebP includes support for lossless encoding and transparency, just like PNG. It has a lossy encoder that is often superior to JPG, and it even has support for animations so that it can sub in for GIF as well. We see an average of 40% savings with the WebP format, though of course that varies from image to image and depends on the original format of the image.
With those impressive savings, you might be surprised to find that WebP is not always better than "legacy" formats, especially when using EWWW IO's Premium compression options. Out that same sample set (over a million images), 6% were not smaller when converted to WebP.
It is also important to note that the WebP format is not supported by all browsers. Or more accurately, it IS supported by all "modern" browsers, but there are still around 5% of folks on the web using older browsers that can't view WebP images.
Keeping both of those things in mind, we recommend "conditional" WebP usage. In other words, EWWW IO will only convert/deliver a WebP image if it is smaller, and if the visitor's browser supports WebP. If you don't care about any of that, WordPress 5.8+ will allow you to upload WebP images directly, use WebP thumbnails and deliver only WebP images to all your visitors. We're not big fans of that approach, but some folks are okay with that method.
One problem with the "conditional" approach is that it requires you to have both the original/legacy version of your image + a new (smaller) WebP version of your images. This can eat up extra disk space, which may be a non-starter for some folks. If you find yourself in that boat, you can get automatic WebP delivery with our Easy IO CDN.