AVIF to JPG or PNG on Windows: what AVIF is, why you're getting it, and how to convert a folder
First it was .webp, now it’s .avif. Same reason, newer codec, and even fewer programs that open it. Here’s what’s going on and how to turn a folder of them into JPG or PNG without uploading anything.
What AVIF is
AVIF is an image stored with the AV1 video codec, the same open codec streaming services use. It compresses smaller than WebP, which compresses smaller than JPEG, and it supports transparency, HDR and animation. Browsers added it from 2020 onwards, and sites that care about page speed now serve it to any browser that accepts it. As with WebP, Save image as gives you the format the site sent; see why Chrome saves images as WebP for the mechanism, which is identical.
Why Windows struggles with it
Browsers all open AVIF. Windows itself, Explorer thumbnails and most desktop programs depend on an optional codec being present, and support has varied by Windows version. If Explorer shows a blank thumbnail for an .avif, that’s the codec gap, not a broken file. Simple Image Converter carries its own AVIF decoder, so it opens the file on any Windows 10 or 11 PC, or on Linux, without installing anything.
Converting a folder
Drop the folder, pick JPG or PNG (or the Web images → PNG preset), Convert All. It decodes AVIF, WebP and HEIC in the same batch, in parallel, and skips anything it can’t read with a reason.
Size and quality, measured
One 2,048 × 1,363 photo (a CC0 image from Wikimedia Commons, encoded to AVIF at quality 60 as a stand-in for what sites serve), converted on 16 Sep 2026 with the app’s decoding library:
| File | Size |
|---|---|
| AVIF, as served (quality 60) | 480 KB |
| → JPG, quality 90 | 1.07 MB |
| → PNG | 4.35 MB |
The JPG is about twice the AVIF; the PNG is nine times. That’s the codec generation gap: AVIF is doing more with fewer bytes. Converting doesn’t add detail, so a high JPG quality (85–90) is right for photos; PNG is only worth it for graphics, screenshots and anything with transparency. Decoding is quick: 12 AVIF files converted to JPG in 0.24 seconds in parallel on an 8-core desktop.
What the app won’t do
Simple Image Converter opens AVIF but can’t save AVIF (or HEIC). Its job is the other direction: getting the modern formats into something every program on your PC opens, for whole folders, offline, on Windows and SteamOS/Linux. One-time purchase on Steam.
Related guides
- WebP to JPG or PNG on Windows: one file, or a whole Downloads folder at once
How to convert WebP images to JPG or PNG on Windows 10 and 11 with Simple Image Converter: why you keep getting WebP, what happens to transparency (tested), and clearing a folder full of .webp files in one pass without uploading anything.
- Why Chrome saves images as WebP (and how to get a JPG or PNG instead)
Chrome isn't converting your images: the website served WebP and 'Save image as' keeps what it received. What's actually happening, why it's happening more, and how to turn the .webp files you've saved into JPG or PNG in one pass with Simple Image Converter.
- Bulk convert HEIC to JPG: whole folders of iPhone photos at once, on Windows or Linux
How to convert hundreds or thousands of iPhone HEIC photos to JPG in one pass with Simple Image Converter: why the usual routes stop at a few files a day, a timed conversion test, what happens to orientation and location data, and a folder walkthrough.