AVIF file format
AVIF squeezes photographs harder than anything else in a browser today, holding acceptable quality at file sizes where JPEG has already fallen apart into blocks.
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What is AVIF?
AVIF arrived in 2019 from the Alliance for Open Media, the consortium behind the AV1 video codec. Like WebP before it, it takes a video encoder's still-frame path and packages it — here as an AV1 keyframe inside the HEIF container. AV1 is a far more sophisticated codec than VP8, with larger and adaptive block partitioning, better prediction and smarter filtering, and the image format inherits all of it.
The practical result shows up at the low end of the quality scale. At file sizes where JPEG produces visible 8×8 blocking and WebP goes soft, AVIF usually still looks clean, which is why it is popular for hero images and thumbnails on slow connections. It also handles 10- and 12-bit colour depth, wide colour gamuts and HDR, none of which classic JPEG can represent at all.
The cost is encoding time. Searching all those coding options is computationally expensive, so producing an AVIF can take seconds where a JPEG takes milliseconds — fine for assets you export once and serve a million times, painful for bulk on-the-fly conversion. Browser support is now broad, but older desktop software and some social platforms still do not accept the format.
| Extension | .avif |
|---|---|
| Category | Image |
| MIME type | image/avif |
| Released | 2019 |
| Developed by | Alliance for Open Media |
| Compression | Lossy or lossless |
| Transparency | Yes |
| Animation | Yes |
AVIF: frequently asked questions
- Is AVIF better than WebP?
- For photographs at small file sizes, clearly — AVIF typically needs 20-30% fewer bytes for the same perceived quality and degrades far more gracefully. WebP still wins on encoding speed and on lossless graphics, and its support in older software is much wider.
- Why does AVIF take so long to encode?
- Because the AV1 encoder evaluates a huge number of block partitions and prediction modes to find the cheapest way to represent each area. That search is what produces the small files, and it costs CPU time. Most encoders expose a speed setting that trades a little compression for a large speed gain.
- Which browsers support AVIF?
- Chrome, Firefox, Edge, Opera and Safari all decode AVIF in current versions, so the web is effectively covered. The gaps are elsewhere: older operating systems, desktop image editors, email clients and some upload forms still do not recognise the format.
- Does AVIF support transparency and animation?
- Yes to both. It carries a full alpha channel, and because it is built on a video codec, animated AVIF is genuinely efficient rather than a hack. Animation support in software is thinner than still-image support, so check your target before relying on it.
- Should I convert my photo library to AVIF?
- Only if storage is the binding constraint and you accept the compatibility trade-off. Re-encoding existing JPEGs adds a second round of loss for a smaller file, and every device that must read the archive needs an AVIF decoder. For a library you intend to keep for decades, that is a real risk.
- Why does my AVIF look worse than expected?
- Usually the quality setting is too aggressive, or the encoder speed preset is too fast to find good partitions. AVIF also smooths rather than blocks when starved of bits, so heavy compression shows as lost fine texture — grass, fabric and hair are where you notice it first.