AVIF is the newest format, and that is the problem
AVIF came out of the AV1 video codec and it is genuinely the best of the common image formats for compression. It regularly produces files half the size of a JPEG at the same visual quality, and it handles transparency, wide colour and high dynamic range, none of which JPEG can do.
It is also very new. Browser support only became broad around 2023, and software support lags browsers by years. So an AVIF you saved off a website will very often refuse to open in the thing you actually need it for: image editors, print shops, job management software, most Windows applications without an extra codec installed, and plenty of phones.
Converting to JPG trades the file size away for the ability to open it anywhere. That is usually the right trade when you need to use the picture rather than serve it.
Expect the file to get considerably bigger
This is the one to brace for. AVIF is so much more efficient than JPEG that converting routinely doubles or triples the file size. A 300KB AVIF can come out as an 800KB JPG carrying exactly the same picture.
That is not the converter doing something wrong. It is the two formats being decades apart in compression technology, and it is the price of universal compatibility. The tool tells you when it has happened rather than quietly handing you a bigger file.
Transparency and colour
AVIF supports transparency and JPEG does not, so any transparent area has to become a solid colour. Left unspecified it would come out black, which is how a logo ends up on a black square. You pick the colour here, and it defaults to white.
AVIF can also carry more colour information than JPEG: 10 and 12 bit depth, and wide gamuts like Display P3. Converting flattens all of that to standard 8 bit. On an ordinary photograph you will not see it. On a graduated sky or a deliberately graded image you might, as faint banding where a smooth gradient had more steps than JPEG can hold.
When to convert and when not to
Convert when something refuses to open the file: older software, a print shop's uploader, a client on an out-of-date machine. Convert when you are sending a picture to somebody whose software you cannot predict.
Do not convert when the image is for a website. You would be throwing away the main advantage of the format and making the page slower, and every current browser reads AVIF fine. And keep the original either way, because you cannot get the quality back from the JPG.
No daily quota, because there is no server to pay for
This runs on the page, in your browser. No upload, no limit on how many files, no maximum size, no watermark, no daily quota and no account. Other converters meter it because server time costs them money; this costs us nothing because it runs on your machine.
One genuine limit: your browser has to be able to decode AVIF in the first place. Current Chrome, Edge, Firefox and Safari all can. If yours cannot, the tool will say so rather than failing quietly.
Common questions
Why can I not open an AVIF file I downloaded?
Because AVIF is very new. Browser support only became broad around 2023, and software support lags years behind, so an AVIF saved from a website will often refuse to open in image editors, print shops' uploaders, most Windows applications, and plenty of phones.
Why does converting AVIF to JPG make the file bigger?
Because AVIF is far more efficient at compression than JPEG, so converting routinely doubles or triples the file size. A 300KB AVIF can come out as an 800KB JPG carrying exactly the same picture, which is the two formats being decades apart in compression rather than anything going wrong.
What happens to a transparent background when converting AVIF to JPG?
It has to become a solid colour, since JPEG cannot store transparency. Left unspecified it would come out black, which is how a logo ends up on a black square, so this tool lets you pick the colour and defaults to white.
Does converting AVIF to JPG lose picture quality?
Some, on certain images. AVIF can carry 10 or 12 bit colour depth and wide colour gamuts such as Display P3, and converting flattens all of that to standard 8 bit. An ordinary photograph will not show it, but a graduated sky or a deliberately graded image might show faint banding.
When should I convert AVIF to JPG, and when should I not?
Convert when something refuses to open the file, such as older software, a print shop's uploader or a client on an out of date machine. Do not convert an image meant for a website, since every current browser reads AVIF fine and converting only makes the page slower.
Is there a limit on file size or number of files, and is anything uploaded?
No. The conversion runs in your browser with no upload, no file size limit, no daily quota and no account. The only real limit is that your own browser has to be able to decode AVIF, which current Chrome, Edge, Firefox and Safari all can.