Format reference · .avif
What is AVIF?
AVIF is a modern image format built on the AV1 video codec. It usually makes the smallest files of the common web formats at similar quality, supports transparency, HDR and animation, and works in all current major browsers. The main cost is slower encoding.
Where AVIF comes from
AVIF stands for AV1 Image File Format. It was published in 2019 by the Alliance for Open Media, an industry group formed to create royalty-free video technology. The idea was simple: take the intra-frame coding of the AV1 video codec and store single images with it.
The container is HEIF, the same box-based structure used by iPhone HEIC photos. The difference is the codec inside: HEIC uses HEVC, which requires patent licensing, while AVIF uses AV1, which was designed to be free to implement. That licensing difference is a large part of why browsers adopted AVIF and not HEIC.
How AVIF compression works
AV1 splits the image into blocks of many different sizes, from tiny 4×4 squares in detailed areas to large blocks in smooth ones. Each block is predicted from its neighbors using dozens of directional modes, and color can be predicted from brightness. The leftover error is transformed and quantized, then several filters clean up edges and ringing after decoding.
Because of these filters, an over-compressed AVIF looks smooth or slightly smeared rather than blocky. Fine textures like grass, fabric or skin pores can lose detail first, so it’s worth checking detailed photos at the quality you choose.
AVIF supports 8, 10 and 12 bits per channel, HDR transfer functions and wide color gamuts, and both subsampled and full-resolution color. A lossless mode exists, but it is often larger than lossless WebP or a well-optimized PNG, so AVIF is mainly used lossy.
Transparency and animation
Transparency is stored as a separate alpha image inside the file, so cut-out photos and logos with soft edges work as expected. AVIF also supports image sequences for animation. Animated AVIF plays in current versions of the major browsers, but tools for creating it are less common than for animated WebP.
Browser and system support in 2026
Chrome has displayed AVIF since 2020, Firefox since 2021, Safari since version 16 in 2022, and Edge since early 2024. On devices, recent macOS and iOS versions open AVIF natively, and Windows 11 shows it with Microsoft’s AV1 extension. Some older software, email clients and upload forms still don’t accept AVIF, so keep a JPG or PNG copy for sharing outside the web.
File size and encoding speed
For photos, AVIF is often 40–50% smaller than a JPG at similar visual quality and usually smaller than WebP as well, though results vary from image to image. Note that AVIF quality numbers aren’t comparable to JPG’s: Pixellin’s default AVIF quality of 60 looks roughly as good as a much higher JPG setting.
The trade-off is time. Encoding AVIF can take seconds per large photo, compared with a fraction of a second for JPG. Pixellin runs it in a background worker so the page stays responsive. Create AVIF with Convert to AVIF or let Optimize AVIF choose the smallest visually identical setting. To go the other way, use AVIF to JPG.
Use AVIF for
- Large photos on websites where every kilobyte counts
- HDR and wide-gamut images on the web
- Hero images and product photos on image-heavy pages
- Transparent photographic cut-outs at a small size
Avoid AVIF for
- Files you send to people with older software or devices
- Workflows that need fast encoding of many images on the fly
- Screenshots and flat graphics where lossless PNG or WebP fits better
- Upload forms and print services that only accept JPG
AVIF questions
Is AVIF better than WebP?
For photos, AVIF usually produces smaller files at the same visual quality, especially at lower file sizes. WebP encodes much faster, has a stronger lossless mode, and is accepted by slightly more software. Many sites serve AVIF first and fall back to WebP or JPG.
Why does AVIF take so long to save?
The AV1 encoder tries many block sizes, prediction modes and transforms to find the most compact result, which costs a lot of computation. That search is what makes the files small. Decoding is fast, so visitors don’t notice the cost; only the person creating the files does.
Can I open AVIF files on Windows?
Windows 11 can display AVIF in Photos and File Explorer once the AV1 Video Extension from the Microsoft Store is installed, and it is preinstalled on many systems. Any current browser also opens AVIF files. If you need it in older software, convert it to JPG or PNG.
Is AVIF the same as HEIC?
No, though they share the HEIF container. HEIC stores images compressed with HEVC, which iPhones use by default. AVIF uses the royalty-free AV1 codec. Browsers broadly support AVIF, while HEIC is mostly limited to Apple devices and Safari.