JXL to AVIF Converter

This conversion narrows compatibility rather than widening it

Almost every conversion on this site solves a problem: the source format is too large, too old, or too narrowly supported. This one does the opposite. JXL has poor support and AVIF has good but not universal support, so converting from one to the other exchanges one limitation for a different one rather than removing it. If the motivation is file size, the conversion is worthwhile. If the motivation is to be able to open the file, it is not, and WebP or PNG is the better answer.

NoteIf the problem is that JXL will not open, AVIF is not the answer. WebP or PNG is.

When smaller is genuinely the goal

There is a clear case for this conversion: an AVIF file is the smallest practical web format, so if a set of images is destined for a website with current-browser traffic and a fallback is available, converting to AVIF reduces the total bytes meaningfully. It also supports 10-bit colour and smooth transparency, so a JXL that uses those capabilities is being moved to a format that handles them well rather than poorly. The requirement is a fallback file, because a browser without AVIF support shows nothing at all.

• A website with current-browser traffic and a WebP fallback.
• A large set where total bytes matter, such as an image gallery.
• A source using 10-bit colour or smooth transparency.
• Keep a WebP version, because a browser without AVIF shows nothing.

NoteServe AVIF with a WebP fallback. Without one, unsupported browsers show nothing.

Two lossy formats and the quality question

Both formats are lossy in their default mode, so a lossy to lossy conversion encodes the image twice and the artefacts compound. Both also have lossless modes, and since JXL is the source, lossless AVIF would preserve exactly what the JXL held. The interesting case is a JXL saved losslessly: converting it to lossy AVIF produces a dramatically smaller file while still looking identical, which is a genuinely useful result. As always, converting from the original rather than chaining avoids the repeated loss.

• Lossy to lossy encodes twice and compounds the artefacts.
• Both formats have lossless modes. Use one if the pixels matter.
• A lossless JXL to lossy AVIF is dramatically smaller and looks identical.
• Convert from the JXL, not from a previous AVIF.

What the file size actually does

AVIF is generally more efficient than JXL in lossy mode, so a conversion often produces a smaller file, unlike the JXL to WebP case. The result depends heavily on the source quality: a JXL saved at maximum quality may convert to a smaller AVIF, while one already at a modest quality may produce something similar in size with slightly different artefacts. The reliable way to know is to convert and compare, which is why the size is shown for each file after processing.

• AVIF is usually more efficient than JXL in lossy mode.
• A high quality JXL often converts to a smaller AVIF.
• A JXL already at modest quality may produce a similar size.
• Convert and compare rather than assuming the direction.