You downloaded an image, it ended in .avif, and your usual app refused to open it. AVIF is a newer, extremely efficient format — great for the web, occasionally annoying everywhere else. Here is what it is and how to deal with it.
We measured this ourselves. While measuring our converters we ran into a hard limit worth knowing: a browser canvas can only encode three formats. Ask Chromium 151 for an AVIF and it hands back a PNG instead. That is why this site converts from AVIF but has no “to AVIF” page — and why the only way to produce AVIF today is a server-side or native encoder. see the full measurements
How small AVIF actually gets. Our 1200 × 800 UI capture fits into 1,472 bytes as AVIF. Converting away from it costs every time: as WebP 1.4 KB → 6.9 KB (+378%), and the flat illustration as PNG 3.2 KB → 90.6 KB (+2704%) — the most lopsided row in our whole table. There is no size argument for leaving AVIF, only a compatibility one. Two honest limits: our test files carry no transparency (the ffmpeg AVIF muxer does not write the alpha item), and we generated them with ffmpeg because a browser canvas cannot encode AVIF at all.
What is AVIF?
AVIF (AV1 Image File Format) is based on the AV1 video codec. It offers some of the best compression available: an AVIF file is often smaller than JPG and WebP at the same quality, and it also supports transparency and HDR. That is why modern websites increasingly serve AVIF.
Why AVIF files are so small
AV1 was designed to stream 4K video efficiently. AVIF borrows that advanced compression for still images, squeezing out detail the eye barely notices far more aggressively than older formats. The result is tiny files with surprisingly good quality.
How small is measurable: our 1200 × 800 UI capture fits into 1,472 bytes as AVIF. For comparison, the same picture needs 36.5 KB as PNG. That is the compression story in one line — and it is why every conversion out of AVIF costs something.
The catch: support is still catching up
Current versions of Chrome, Edge, Firefox and Safari can display AVIF, but:
- Many desktop apps, older phones and some editors still cannot open
.avif. - Some upload forms and printers reject it.
- Colleagues on older software may not see it at all.
That is why “how to open an AVIF” is such a common question — the file is fine, your software just does not speak AVIF yet.
How to open or convert an AVIF
The simplest fix is to convert it to a universally supported format. These tools run entirely in your browser — your image is never uploaded:
- AVIF to JPG — best for photos and for sharing anywhere.
- AVIF to PNG — when you need lossless quality or transparency.
- AVIF to WebP — stay modern and small, with wider support than AVIF.
The costs, measured on our own pages: the flat illustration went 3.2 KB → 23.5 KB as JPG (+626%), and that UI capture 1.4 KB → 36.5 KB as PNG (+2442%). Neither is a defect — you are leaving the most efficient codec in our table, so the only reason to do it is compatibility.
Should you use AVIF yourself?
If you run a website and want the smallest images, AVIF is excellent — pair it with a JPG or WebP fallback for older clients. For files you hand to other people, convert to JPG or PNG so they open everywhere.
AVIF vs. HEIC vs. WebP
AVIF is easy to confuse with two neighbours:
- HEIC — the format an iPhone saves photos in. It uses a similar container to AVIF but a different, patent-encumbered codec (HEVC). AVIF is royalty-free and openly standardised by the Alliance for Open Media, which is a big reason browsers adopted it and not HEIC. Got iPhone photos to open? See how to convert HEIC to JPG.
- WebP — older and more broadly supported, but usually a little larger than AVIF at the same quality. The full three-way comparison is in AVIF vs WebP vs JPEG.
The three-way comparison is usually made with codec generations. Ours is made with bytes, by converting out of AVIF into WebP and seeing what the older codec charges:
| Test image | Input | Output | Change |
|---|---|---|---|
| Photo | 122.3 KB | 234.4 KB | +92% |
| Screenshot | 1.4 KB | 6.9 KB | +378% |
| Illustration | 3.2 KB | 9.9 KB | +208% |
The illustration went 3.2 KB → 9.9 KB (+208%) and the photo 122.3 KB → 234.4 KB (+92%). WebP is one codec generation behind and pays for it most on synthetic images, least on photographs — the same ordering HEIC sits in, since HEIC and AVIF share the HEIF container and differ mainly in the codec inside (HEVC versus AV1). What separates them in practice is not efficiency but licensing: AV1 is royalty-free, which is why browsers shipped AVIF and never shipped HEIC.
Common misconceptions
- “AVIF is a video format.” No — it stores a single still frame (or an animation) using AV1’s intra-frame compression. The
.avifyou downloaded is an image, not a clip. - “AVIF is always lossless.” It is lossy by default, just very efficient. It does have a true lossless mode, but that produces noticeably larger files.
- “If it won’t open, the file is broken.” Almost never. A
.avifthat fails to open just means the app is older than the format — the file itself is fine.
FAQ
Is it safe to use AVIF on a live website?
Yes, as long as you provide a JPG or WebP fallback (the <picture> element does this automatically) for the few visitors on older software.
Can I attach an AVIF to an email?
You can, but the recipient may not be able to open it. Convert it to JPG first to be safe.
Does saving as AVIF reduce quality?
At sensible quality settings the loss is invisible, but like any lossy format, repeatedly re-saving the same file will slowly degrade it.