Knowledge
WebP versus AVIF in WordPress: which do you choose?
WebP and AVIF are both modern image formats that are much lighter than JPEG and PNG. The question isn't which format wins, but which format you can best use per visitor and per file.
In short
- AVIF usually compresses most strongly, WebP is more widely supported
- A fallback keeps older browsers working
- Spark automatically delivers the format the browser can handle
The differences at a glance
WebP has been around longer and is supported by virtually every modern browser. AVIF is newer and often achieves a smaller file at the same quality, especially for photos with lots of color gradients, but encoding takes more processing time.
- AVIF: smallest files, slightly heavier encoding
- WebP: nearly universal support, quick to create
- JPEG and PNG: as fallback for older browsers
Why you don't have to choose
You don't need to lock in one format for your entire site. Spark Media Optimizer determines which format each visitor's browser supports and serves that, with a clean fallback to an older format where needed.
This way a modern browser gets the lightest variant, while an older browser simply sees a working image. You don't need to write any separate rules or shortcodes for this.
Tip: enable AVIF for your photo-heavy pages and let WebP handle the broader work. The fallback ensures nobody ends up with a blank box.
Let Spark automatically choose the best format per browser.
Frequently asked questions
Most modern browsers do, but not all of them. That's why Spark provides a fallback, so older browsers get a WebP or the original instead of nothing.
The encoding happens in advance in the background, not during the visit. The visitor only sees the ready-made, lighter file.
Yes. You can set up your profile so that Spark delivers WebP with a classic fallback, if you want to skip AVIF for now.