Serving AVIF as the only format on a site with no JPEG or WebP fallback for software that cannot decode it.
File formats
AVIF
Also called .avif or av1 image file format. Here is what it means, when it changes what you export, and what people get wrong.
File formatsRuns on your deviceUpdated 10 August 2026
The short answer
AVIF stores AV1-coded pictures inside a HEIF container. It compresses harder than JPEG or WebP at comparable visual quality and adds 10- and 12-bit colour, HDR, wide gamut, full alpha transparency and image sequences, at the cost of slower encoding and patchier support outside browsers.
Updated
The short version
AVIF at a glance
| Quick fact | Detail |
|---|---|
| Codec | AV1 intra coding, royalty-free |
| Container | HEIF, based on ISOBMFF |
| Bit depth | 8, 10 or 12 bits per channel |
| Transparency | Yes, full alpha channel |
| HDR and gamut | Yes, high dynamic range and wide gamut |
| Animation | Yes, via image sequences |
Slide the table sideways to see every column.
What is actually inside an AVIF file?
Two separate pieces of engineering. The picture itself is encoded with AV1, a royalty-free video codec, using the tools it applies to a keyframe. That encoded picture is then wrapped in the HEIF container, which is built on the same ISO base media file format used by MP4.
The container is why AVIF can do more than hold one photograph. It stores independently addressable items, so a file can carry the main image, an alpha mask as an auxiliary item, a thumbnail, colour and metadata boxes, and a sequence of frames. Tiling lets a decoder work on regions in parallel, which matters for large images.
Why does AVIF compress better than JPEG?
Because it is thirty years of codec research newer. JPEG works in fixed 8 x 8 blocks with one transform and no spatial prediction. AV1 uses variable block sizes down to small detail and up to large flat regions, a wide set of directional intra-prediction modes, several transform types, and a much stronger entropy coder. It also has loop filters that suppress the block edges JPEG makes visible.
The practical effect is largest where bytes are scarcest. At aggressive compression AVIF holds together while JPEG breaks into blocks and ringing, and it degrades into softness rather than into visible structure. At very high quality settings the advantage narrows, because there is less to be clever about when almost nothing is being discarded.
What does AVIF do that WebP cannot?
| Capability | AVIF | WebP |
|---|---|---|
| Bit depth | 8, 10 or 12 bits per channel | 8 bits |
| HDR and wide gamut | Yes | No |
| Chroma sampling | 4:2:0, 4:2:2, 4:4:4 and monochrome | 4:2:0 in lossy mode |
| Alpha transparency | Yes, full alpha | Yes, full alpha |
| Animation | Yes, image sequences | Yes |
The bit depth and gamut columns are the ones that change what is possible rather than just what is smaller. A 10-bit AVIF can hold a smooth sky without the banding an 8-bit gradient shows, and it can describe colours outside sRGB, which matters for images shot on modern phones in Display P3.
What are the practical downsides?
Encoding is the main one. AV1 spends far more computation searching for the best coding decisions than JPEG does, so a batch conversion that would take seconds in JPEG can take minutes. Encoders expose speed presets, and the fast presets give up some of the compression advantage in exchange for reasonable times.
Beyond that, support outside web browsers is uneven. Many desktop editors, print workflows and marketplace upload forms still do not accept AVIF, and there is no CMYK support, so it has no role in prepress. Decoding also costs more CPU than JPEG, which is noticeable on older phones when a page loads many images at once. Treat AVIF as a delivery format for your own site, keep a lossless master, and export JPEG or PNG when uploading somewhere that specifies them.
What people get wrong about avif
Each one is a real failure mode, not a style preference.
Expecting an AVIF converted from an 8-bit sRGB JPEG to gain HDR or wide gamut, when the source never had them.
Batch converting a large archive at the slowest encoder preset and being surprised it takes hours.
Uploading AVIF to a marketplace whose published image requirements list only JPEG and PNG.
Questions people ask
AVIF, answered
The follow-up questions people search for once they have the definition.
Is AVIF better than WebP?
For compression and capability, generally yes: smaller files at the same quality, plus 10- and 12-bit colour, HDR and wide gamut that WebP does not offer. WebP encodes much faster and is supported in more non-browser software, so it remains the easier default for bulk work.
Does AVIF support transparent backgrounds?
Yes. Alpha is stored as a separate auxiliary image inside the container, at full 8-bit or higher precision, so edges can fade smoothly. A cut-out product shot in AVIF is usually much smaller than the same cut-out as a transparent PNG.
Can AVIF files be animated?
Yes, through image sequences in the HEIF container, with per-frame timing and looping. In practice a real video file is still more efficient for anything longer than a few seconds, so animated AVIF suits short loops rather than clips.
Why does saving an AVIF take so long?
AV1 encoding searches a very large space of block sizes, prediction modes and transforms to find the smallest result. That search is what buys the compression advantage. Using a faster encoder speed preset cuts the time substantially and gives up only part of the size benefit.
Should I use AVIF for marketplace listing photos?
Usually not. Selling platforms publish their accepted formats and most still specify JPEG or PNG, so an AVIF upload risks being rejected. Use AVIF on your own website where you control delivery, and export JPEG for listings.
Same cluster
More from the glossary
Neighbouring entries, so every term in the set is one hop from every other.
Background removal
Background removal separates the subject of a photo from everything behind it and discards the rest, leaving either a transparent cut-out or the subject on a new backdrop.
Aspect ratio
Aspect ratio is the relationship between an image's width and its height, written as two numbers such as 1:1, 4:5 or 16:9.
Banding
Banding is when a smooth gradient breaks into visible steps or stripes instead of blending.
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Sources
Where the facts on this page come from. Every link opens the specification, standard or documentation the claim was read at.
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