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AVIF
What is an AVIF file?
The most efficient web image format today. Smaller than WebP, slower to encode.
What AVIF is
AVIF is a container: a wrapper that holds streams encoded by something else. It stores a grid of pixels, so enlarging it past its own resolution softens it. It is used for the web and handing a finished file over.
The extension is .avif, and the full name is AV1 Image File Format. Both matter less than what the file can hold, which is what the rest of this page is about.
Where AVIF came from
Alliance for Open Media published it in 2019. The specification is AV1 Image File Format.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification is public
Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.
Nothing is thrown away
AVIF stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.
It can be transparent
AVIF carries an alpha channel, so a logo keeps its soft edges over whatever sits behind it instead of arriving in a white box.
It can hold more than one frame
AVIF can store an animation rather than a single still. That is worth knowing before converting one: a target that holds one frame keeps the first and drops the rest, usually without saying so.
Colour it can describe
Up to 12 bits per channel. It can work in RGB, YCbCr, the model video and JPEG compress in and wide-gamut colour.
More than eight bits per channel is what stops a gradient from stepping when it is edited, which is why it matters in a working file and rarely in a finished one.
There is a size limit worth knowing
AVIF cannot describe an image larger than 65,536 pixels on a side. That is far beyond an ordinary photograph and well within reach of a stitched panorama or a high-resolution scan, which is exactly when people meet it.
AVIF is a box, and the codec is what is in it
It usually holds AV1. This is the distinction behind most "why will this not play" questions: two files with the same extension can contain entirely different encodings, and a player that refuses one may be perfectly happy with the other.
It also explains why changing container is often fast and lossless while changing codec is neither. Moving the same stream into a different box rewrites the box; re-encoding rewrites the picture.
What opens AVIF
GIMP, Squoosh and ImageMagick read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
Current browsers read it; older ones do not.
Where support is uneven, serving a second format alongside it is the usual answer — the browser takes the one it understands and nobody is left out.
What it can carry besides the content
AVIF can hold EXIF, XMP and ICC profiles.
Whether any of it survives a conversion depends entirely on the target, and the honest answer is usually "some of it".
It is a delivery format
AVIF is meant to be handed over rather than worked in. Editing one is possible and rarely pleasant; the sane approach is to change the source and export again.
What goes wrong with it
The recurring complaints: it is slow to write compared with its neighbours.
None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.
The facts, in one place
| Extension | .avif |
|---|---|
| Media type | image/avif |
| Published by | Alliance for Open Media |
| First published | 2019 |
| Specification | AV1 Image File Format |
Converting AVIF to something else
Converting something else to AVIF
Formats worth considering instead of AVIF
Where these figures come from
The claims on this page are checkable, and these are the documents that settle them.