AVIF: efficient on the web, awkward elsewhere
AVIF, the AV1 Image File Format, stores still images with the compression developed for the AV1 video codec. It is one of the most efficient image formats in common use, which is why many websites and image services now deliver pictures as AVIF: the same photo usually takes noticeably fewer bytes than a JPG. It also supports transparency, wide colour, HDR and animation.
All current major browsers display AVIF, so you rarely notice it while browsing. You notice it when you save an image and get a .avif file that your photo viewer, office software, older image editor, print service or upload form refuses. JPG has been around since the early 1990s and is accepted practically everywhere, which makes it the easiest way to make such an image usable.
What to expect from the JPG
AVIF images are usually lossy and JPG always is, so converting means decoding the AVIF and compressing the pixels again with an older, less efficient method. Two things follow. The JPG will typically be larger than the AVIF, sometimes considerably, to look about the same. And it cannot contain more detail than the AVIF had: any smoothing or blurring from aggressive AVIF compression is carried over as it is.
At the default quality of 90 the new round of compression is usually hard to spot. If the file comes out larger than you need, reducing the dimensions with Settings → Size often helps more than lowering the quality. The aspect ratio is kept, and the fit option never enlarges an image.
A few details are handled during conversion. EXIF metadata is not copied. Colours are converted to sRGB, so wide-gamut images may look slightly less saturated. And because browsers work with 8 bits per channel, AVIF images stored at a higher bit depth are reduced to 8 bits per channel, which is also all JPG can hold.
Transparency and animation
AVIF can store transparency; JPG cannot. Transparent and semi-transparent pixels are blended over the background colour you choose before converting, white by default. Soft edges stay smooth, and fully transparent areas become solid colour. Pick the colour of the page, slide or document the image will sit on, or convert AVIF to PNG if the transparency itself has to survive.
Animated AVIF files are converted from their first frame only, because a JPG holds a single still image.
AVIF vs JPG
| AVIF | JPG | |
|---|---|---|
| Compression | Lossy or lossless, based on AV1 | Lossy |
| Size of a photo | Small | Usually larger at similar visual quality |
| Transparency | Supported | Not supported; filled with a background colour |
| Animation | Supported | Not supported |
| Bit depth | 8, 10 or 12 bits per channel; HDR possible | 8 bits per channel |
| Web browsers | All current major browsers | All browsers |
| Other software | Support still patchy | Accepted almost everywhere |
Before you convert a batch
- Browser: AVIF is decoded by your browser itself, so you need a current Chrome, Edge or Firefox, or Safari 16.4 or later.
- Batches: up to 10 images at a time, converted one after another and downloadable together as a ZIP.
- Keep the AVIF for the web: if the image is going back onto a website, AVIF is already the lighter format. Convert only the copies that need to travel elsewhere.
- Convert once: each lossy conversion loses a little, so avoid passing the same image back and forth between formats.
- Mislabelled files: files are identified by their content, not their name, so an AVIF saved with the wrong extension is still recognised.