Why AVIF?
AVIF is based on AV1, a royalty-free video codec developed by the Alliance for Open Media, whose members include Google, Mozilla, Apple, Microsoft and Netflix. Applied to still images, AV1’s advanced prediction and filtering tools produce remarkably small files. Compared with JPG, AVIF avoids blocky artefacts at low bit rates, handles smooth gradients such as skies far better, and supports transparency, HDR and wide colour gamuts.
For website owners, the attraction is simple: images that are roughly half the size of JPGs load faster and improve Core Web Vitals, particularly Largest Contentful Paint, which is often a photo.
The trade-offs
AVIF has two practical costs. First, encoding is slow; this converter uses a fast encoder setting to keep the wait reasonable, but it will still take noticeably longer than JPG or WebP. Second, support outside browsers is incomplete: some image editors, content management plugins, email clients and social platforms do not accept AVIF. Treat AVIF as a delivery format for your own website and keep the original JPGs as masters.
How the conversion works
The JPG is decoded with MozJPEG’s decoder in a background Web Worker and rotated according to its EXIF orientation. The pixels are then encoded with libavif using the libaom AV1 encoder, compiled to WebAssembly. Camera metadata is not carried over. Everything runs on your device.
Is the wait worth it?
For a handful of hero images or a product catalogue that will be viewed thousands of times, yes: you pay the encoding time once, and every visitor benefits from the smaller download. For quick one-off sharing, WebP or JPG is the more practical choice.
Getting the best results
- Resize before converting. Encoding time grows with pixel count, and few web layouts need more than 2000 pixels; use Resize Image.
- Compare at 100% zoom. AVIF can smooth very fine texture such as grass; raise the quality if detail matters.
- Serve with a fallback if you must support very old browsers, using the HTML
<picture>element with a JPG or WebP source.
For a faster alternative with excellent support, try JPG to WebP.