Why turn a WebP into a AVIF
Both formats are meant for the web, and AVIF is the smaller of the two, commonly by a third to a half. If you already serve WebP and want the page lighter still, this is the step, and transparency survives it.
Convert WebP to AVIF
Squeeze a web picture down one more step.
This file stays on your device
Drop files here
Up to 30.0 MB
Lower makes a smaller file.
What the change costs
Encoding is noticeably slower, and the picture is compressed a second time. Convert at a high quality setting so the second pass does not show.
When to do something else
The gain is only worth having if you serve the file to many people. For a handful of pictures the WebP is already small enough.