What is AVIF? Strengths, support and caveats

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AVIF is the newest of the mainstream web image formats, and it comes with the usual newcomer story: impressive compression, patchy tool support. This guide is a checklist you can run against your own situation, after a short explanation of what the format is.

What AVIF is

According to the specification published by the Alliance for Open Media, AVIF is the AV1 Image File Format. It defines how images compressed with the AV1 video codec are stored inside the HEIF file format, which is itself based on the ISO base media file format. In plain terms, it takes a video compression method and applies it to a still picture, then wraps the result in a container. MDN describes it as an open source, royalty-free format.

The version of the specification I read is 1.2.0, labelled "AOM Final Deliverable, 16 October 2025", with editors from Google and Apple. The recommended file extension is .avif and the media type is image/avif.

What it can store

From the specification and MDN:

• Still images, stored as AV1 image items.
• Image sequences, stored as AV1 tracks, for animation.
• Transparency, through an auxiliary AV1 bitstream. Other data such as depth maps can be carried the same way.
• HDR and wide colour gamut, which the specification states directly.
• Bit depth: AV1 covers 8, 10 and 12 bits.
• Lossy and lossless modes, according to MDN.

MDN also says AVIF compresses roughly 50% smaller than JPEG at comparable quality. That figure comes from MDN's description, not from my test, and it will not hold for every image. web.dev adds a useful reminder: lossy AVIF discards information, so some colours may differ from an equivalent JPEG.

A small measurement

I checked how much the quality setting alone changes an AVIF's size, using Python's Pillow library (version 11.3.0, with AVIF support). The test image is a 1200 x 800 pixel photo-like picture generated by script, smooth gradients with noise and a slight blur. Smooth synthetic images flatter modern codecs, so this is an illustration, not a benchmark.

I did not compare these with JPEG or WebP because quality scales differ between encoders and I did not judge the pictures visually, so equal numbers would not mean equal appearance. The practical point is that the setting has a very large effect, so look at the result before you choose.

Checklist: should you use AVIF for this image?

Work through these in order. A "no" on any early item is usually enough to choose another format.

1. Is it for a web page or app you control? If you control the page, you can serve AVIF with a fallback. If you are sending the file to a person, a form or a print service, choose JPEG or PNG; support in everyday software can be less certain than in browsers, and I did not verify any particular list.

2. Do your visitors' browsers support it? MDN lists AVIF support from Chrome 85, Edge 121, Opera 71, Firefox 93 and Safari 16.1, and notes Firefox 113 and later support animation. Can I use, checked on the same day, gives different first versions for two browsers: Safari 16.4 for full support, with 16.1 to 16.3 marked partial, and Edge 121, with some earlier Edge versions having AVIF disabled by default. It also showed Firefox 77 to 92 as disabled by default. Where sources differ, trust the more cautious one. Can I use showed a global usage figure of 96.35% on 2026-11-03; that number changes, so check it again if it matters.

3. Have you provided a fallback? MDN says support "is not yet comprehensive" and recommends the HTML picture element with WebP, JPEG or PNG sources. web.dev gives the same advice. A fallback also protects older phones and in-app browsers.

4. Is the image large? MDN notes AVIF has no progressive rendering, so files must be fully downloaded before they can be displayed. For a large hero image on a slow connection, that is worth testing.

5. Do you need to edit or archive it? Keep your original. A lossy AVIF made from a JPEG adds a second round of loss, and it cannot give back detail the JPEG already dropped.

6. Does the result actually look good and come out smaller? Compare at full size and compare file sizes. If the AVIF is not clearly lighter, stay with what you have.

Where AVIF fits next to the others

Against JPEG, AVIF aims for the same job with smaller files. Against WebP, it is newer, and both aim at the same web uses; AVIF vs WebP compares them directly. For background on the formats it competes with, see what is WebP and what is JPEG. If you want a plain decision guide across all of them, the best image format for websites, email, print and social covers it.

What ConvertMango can do today

AVIF conversion is planned and not available, so there is no AVIF tool to link. If you have an AVIF file that someone's software will not open, the usual route is to re-export it from the original source. For making a lighter web copy of a JPG, the live JPG to WebP tool works in your browser and needs a browser that can export WebP. It handles one image at a time up to 50 MB and 40 megapixels, and file contents are not uploaded to our conversion service.

Convert it now: JPG to WebP.

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Sources

Plain-text references. Facts that could not be checked against a primary source were left out.

1. Alliance for Open Media, 'AV1 Image File Format (AVIF)', https://aomediacodec.github.io/av1-avif/
2. MDN Web Docs, 'Image file type and format guide', https://developer.mozilla.org/en-US/docs/Web/Media/Guides/Formats/Image_types
3. web.dev, 'Choose the right image format', https://web.dev/articles/choose-the-right-image-format
4. Can I use, 'AVIF image format', https://caniuse.com/avif