Convert AVIF to JPG

AVIF arrived in 2019 from the Alliance for Open Media and it won the argument it was built for: every current browser reads it, which is why sites serve it and why the file you are holding is one. Every current browser is also the entire list. The moment the picture has to go somewhere that is not a browser — a form with an accept list, a phone gallery, an image editor, a print order — the format that won stops being an advantage and becomes the obstacle.

JPEG has been the answer to that since 1992, published as ITU-T T.81, and there is essentially no software that reads pictures at all and does not read it. That is the entire trade on this page: you give back the compression AVIF earned and you receive a file nobody has to be told how to open. If the destination expects a document rather than a picture — something to be attached, printed or filed — a PDF wraps it better, and that is a different page.

AVIF has a lossless mode, and an image served to make a web page load faster is not using it. So the picture has already been through one lossy encoder, and converting it to JPEG sends it through a second one built on entirely different assumptions. Generation loss is the failure mode listed against JPEG in this registry, and two encoders in series is precisely the situation that produces it.

The second encoder cannot see what the first removed. It sees only the result and removes more, guided by a model from 1992 applied to an image shaped by a model from 2019. At a sensible setting the damage is modest and it is not evenly spread: it concentrates where AVIF was cleverest, in smooth gradients, out-of-focus backgrounds and flat areas next to hard edges. Judge the result by looking at those, not at the sharp subject in the middle, which will look fine either way.

The quality control on this page starts at 82. That is a deliberately conservative JPEG setting — high enough that a second pass is hard to see on a photograph, low enough that the file is not absurd for something that only has to be opened and looked at.

The trap is arriving with AVIF instincts. AVIF holds together at numbers JPEG cannot: quality 50 is frequently indistinguishable from the original as an AVIF and is visibly broken as a JPEG, all blocking and mush. If you have been compressing AVIFs and have learned to read the slider one way, read it the other way here. In the other direction, past about 90, the JPEG grows quickly in exchange for a difference nobody sees on a screen. The numbers are not a shared scale between codecs at all — they are each encoder’s own dial, and the only thing they have in common is the direction they point.

AVIF carries a full alpha channel and JPEG carries none. That is a flat difference between the two specifications rather than a limitation of this converter, so anything transparent in the source has to become some colour. The page asks which, and the answer defaults to white.

The fill and any resize happen in one pass over the pixels, which matters more than it sounds. Filling first and scaling afterwards blends the fill into the edges; scaling a transparent image and filling afterwards leaves a fringe of half-transparent pixels that the fill then darkens into a visible halo. Doing both in a single draw avoids both faults. If the picture is a cut-out logo headed for a coloured page, set the background to that colour here rather than repairing a white box later.

AVIF can describe up to twelve bits per channel and wide colour gamuts. JPEG is eight bits, in RGB, greyscale or YCbCr, and has been since it was standardised. If the AVIF came out of a modern camera or an HDR export rather than off a web page, some of what it holds cannot be written into a JPEG at all.

It is worth knowing that the reduction happens before the JPEG encoder is reached: this engine decodes every image into an eight-bit RGBA buffer, so a twelve-bit source is cut down at the decode step whatever the target format is. For the great majority of pictures saved from web pages that costs nothing, because they were eight-bit when they were served. For a wide-gamut original it means the result is a narrower-gamut copy, and the colours can land slightly differently in the most saturated parts of the picture.

This surprises people and it should not. The AVIF exists because it was the smallest thing the browser could be handed, and a JPEG of the same picture at a quality where it looks the same is normally a good deal bigger. Converting for compatibility costs bytes, and the bytes are what the compatibility is bought with.

How much bigger depends entirely on the content. Photographs are where AVIF is strongest, so photographs are where the JPEG grows most. Flat graphics, icons and screenshots are where AVIF is weakest, and there the gap narrows to very little — though for that sort of image PNG is usually the better target than JPEG anyway. If the size matters to you, convert one representative file and measure it rather than trusting a general figure, this one included. The one lever that reliably shrinks the result is the maximum width: fewer pixels is a real saving, where a lower quality number is a saving you can see.

The list of places that take a JPEG and refuse an AVIF is long and boring, and every entry on it is somebody’s actual afternoon: an application form that validates by extension, a photo library that will not index the file, a print service whose uploader rejects it, an email client that shows a broken icon, a colleague on an older machine, a piece of software written before 2019 that by definition never heard of the format.

Universality is the only advantage JPEG has left over AVIF, and it is enough, because the cost of a file the recipient cannot open is not a small penalty — it is total. Nothing about the conversion has to be optimal for it to be right. A slightly larger, slightly softer file that opens is worth more than a perfect one that does not, and thirty-odd years of every camera, phone, scanner and photo library writing JPEGs is not a lead any newer format closes quickly.

If the AVIF came out of your own pipeline, the JPEG should be made from whatever produced the AVIF, not from the AVIF. One lossy encode from a master beats two in series every time, and the master is usually still sitting in the folder the export came from.

If you saved the file from somebody else’s website then you have no master, this is the best available, and no converter can restore detail the site chose not to send. Knowing which of the two situations you are in is worth thirty seconds, because in the first one the better result is free and in the second one there is no better result to find.

The conversion decodes to pixels and encodes again, so the EXIF block does not come across, and nothing on the page changes that. The encoder is handed an array of pixels and nothing else, which means the capture fields are already gone by the time the JPEG is written; a switch offering to keep them would be a promise the engine breaks silently.

For this pair it usually costs nothing. An AVIF that came off a web page has generally been through a resizing pipeline that dropped the camera fields long before you saved it. Where it does matter is the expectation in the other direction: JPEG can carry EXIF, XMP, IPTC, ICC and GPS blocks, so people assume the output has them. It does not. If the capture date or the coordinates need to be in the JPEG, they have to be written there from the original.

jSquash decodes the AVIF and encodes the JPEG inside the browser tab, on your own processor, so the picture never leaves the machine and there is no queue, account or daily allowance. The free ceiling is 100 MB per file, which for a still image is far beyond anything a website will ever have served you. The maximum width control sits at 0, meaning keep the original size — set it if the form at the other end has a pixel limit.

One behaviour worth knowing: the AVIF decoder is strict, and when it rejects a file it returns nothing rather than raising an error, so the page reports the file as unreadable instead of guessing at it. That is nearly always a file that was renamed to `.avif` rather than converted into one. A folder of genuine AVIFs converts in a single pass and comes back as a ZIP.