What Is an AVIF File — and How Do You Open or Convert It?

You save an image from a website and get a .avif file. Windows Photos shrugs, your photo editor refuses it, and the upload form you needed it for says "JPG or PNG only". AVIF files are suddenly everywhere because they're excellent for websites — and mildly infuriating everywhere else. Here's what you're dealing with and the fastest way through it.

What AVIF actually is

AVIF (AV1 Image File Format) is an image format built on the AV1 video codec — the same compression technology behind modern streaming. That ancestry gives it the best compression of any mainstream image format: AVIF files are typically about half the size of an equivalent JPG and noticeably smaller than WebP at the same visual quality, with support for transparency, HDR and wide color. That's exactly why performance-conscious websites serve their images as AVIF — and why the images you save from them arrive in a format your older software has never heard of.

Why half your apps won't open it

Browsers moved fast — every current version of Chrome, Firefox, Safari and Edge displays AVIF fine. Desktop software moved slowly: older image editors, Office versions, printers' upload portals, government forms and plenty of phone apps still expect the formats of 2005. The file isn't broken; the app is behind.

The 10-second fix: convert it

Drop the file into FileLark's AVIF to JPG converter — or AVIF to PNG if the image has transparency you need to keep, or AVIF to WebP for a web-friendly middle ground. Conversion happens in your browser (nothing is uploaded), works in batches, and takes about a second per image. JPG is the "works absolutely everywhere" choice; PNG when you need lossless quality or transparency.

Going the other way

Running a website? Converting your images to AVIF is one of the easiest page-speed wins available — JPG to AVIF and PNG to AVIF routinely halve image weight, which feeds straight into Core Web Vitals and rankings. See our WebP vs AVIF vs JPG comparison for when each format earns its place.

Quick answers

Is AVIF better than JPG? Technically, clearly yes — smaller, richer, more capable. Practically, JPG still wins wherever compatibility matters. Does converting AVIF to JPG lose quality? Marginally — both are lossy formats, but at 85–90% quality the difference is invisible; use PNG if you want zero loss. Why do saved website images keep coming out as AVIF? Because that's what the site serves modern browsers. Converting after saving is simpler than fighting it.