Convert AVIF to JPG

Going from a newer format to an older one

This conversion almost always makes the file bigger, and that is not a fault — it is the whole reason AVIF exists. AVIF routinely stores a photograph at half the size of a JPEG that looks the same, so undoing it costs what it saved. Convert for compatibility, not for size: there is no benefit here beyond being readable by things that cannot read AVIF, which is still a long list — older phones, email clients, print workflows, and a great deal of desktop and enterprise software.

Three of AVIF's capabilities have no home in a JPEG and are lost at the border. Transparency is flattened onto a background colour, because JPEG has no alpha channel and never will. High dynamic range — AVIF can carry 10 and 12 bits per channel with a wide gamut — is tone-mapped down to ordinary 8-bit colour, so a picture that glowed on an HDR screen comes back looking flat, and no amount of editing afterwards recovers it. Animation converts as the first frame only.

The quality setting deserves a moment of thought, because you are re-encoding something that was already encoded. The AVIF's own compression is already baked into the pixels, and the JPEG encoder cannot tell the difference between picture detail and someone else's artefacts — it will faithfully spend bits preserving both. Around 85 is the point where the JPEG stops adding damage of its own; going lower compounds two generations of loss, which looks noticeably worse than a single pass at the same size.

The pixel data is what survives; the file's notes about itself mostly do not. Camera settings, capture date and location stored in the AVIF are not carried across — usually welcome when a picture is going somewhere public, and worth knowing if you were relying on them.

When you want something else

If the destination can read AVIF, do not convert. Keeping the original is strictly better on every axis — smaller, higher quality, more colour — and the compatibility problem is shrinking every year.

For a folder of them, or for control over the tone mapping that HDR content needs, avifdec in.avif out.png decodes without touching quality and lets you encode the JPEG separately with cjpeg or mozjpeg — mozjpeg in particular produces a visibly better file at the same size than any browser encoder. ImageMagick's magick in.avif -quality 88 out.jpg handles a whole directory in one line.