What AVIF is
AVIF is a picture stored with AV1, the video codec designed to beat older video compression. Used on a still image, it often produces a much smaller file than JPEG for a similar look, and it can hold more of the quiet areas of a photo without the familiar JPEG blocks. You meet it in the same places you meet WebP, only a step newer: a news site or a shop whose CDN rewrites images, a browser that saved exactly the bytes it was sent, a screenshot tool, occasionally a camera or a phone that offers it as an option. The file extension is .avif. The picture looked normal on the page. The trouble starts when something else has to open the file.
That something else is often boring and specific. A learning-management upload that sniffs extensions. A print dialog. An email client that shows an empty thumbnail. A relative's laptop. JPEG is still the file those systems mean when they say “a normal image.” Converting is a compatibility move. It is not an upgrade in sharpness.
Why your browser matters
This page does not include its own AVIF decoder, and it does not send the file to one. It asks the browser to decode the image, draws the result on a canvas, and writes a JPEG. That is deliberate. An AVIF decoder is a large piece of code, and a server-side fallback would mean uploading the photo. The privacy line above the drop zone would be false the moment a failed file was retried somewhere else.
Current versions of Chrome, Edge, and Firefox decode AVIF. Safari added support later, and a fully updated Apple browser usually can. The failures show up in older versions, in in-app web views, and in locked-down environments that froze their browser. When decoding fails, the row says this browser could not decode the AVIF and that the file was not sent anywhere. Open this same page in a current Chrome, Edge, or Firefox, and add the file again. You are still converting locally. You have only changed which decoder is available.
A file that is not AVIF at all fails too. Renaming a JPEG or a WebP to .avif does not change the bytes. The browser has to recognize an AVIF image.
Quality, transparency, and what the JPEG contains
The slider is JPEG quality, starting at 92. AVIF files are often so small that the JPEG comes out larger. That is the trade. Lower the slider for a chat attachment. Keep it high if the JPEG will be cropped or printed. Changing it re-encodes from the pixels already decoded in the tab.
JPEG cannot store transparency. Transparent pixels are drawn over white. If you needed a cut-out with a real alpha channel, a JPEG is the wrong destination. This site does not currently offer AVIF to PNG. The honest options are a desktop tool that writes PNG, or an editor that can open the AVIF itself.
You get one image, the bitmap the browser returned. Animated AVIF and image sequences are not split into frames. EXIF and other metadata are not copied into the new JPEG, including GPS coordinates and capture time. Orientation follows the browser's decode, so the picture should be upright. If you needed the original metadata block, convert with a tool that copies it. FromHEIC never receives the file, so there is nothing stored here to recover later.
Several files can go through together. Each row is independent, so one undecodable AVIF does not cancel the rest. Download all as ZIP packs the JPEGs that succeeded. There is no watermark and no account. Memory in the browser is the limit that matters for a large batch.
Questions
What is an AVIF file?
AVIF is a still image compressed with AV1, the same codec family used for a lot of modern video. It can be much smaller than JPEG at a similar visual quality. Browsers, CDNs, and a few cameras and screenshot tools have started writing it. Desktop apps and upload forms are behind.
Why does this page sometimes refuse a file my friend opened?
Because decoding is done by the browser you are using, not by a decoder we ship and not by a server. Chrome, Edge, and Firefox have decoded AVIF for a while. Safari added it later. In-app browsers and older versions still fail. Open the same page in a current desktop browser and add the file again. It is not uploaded in either case.
Can you convert it on a server if my browser cannot?
No. FromHEIC does not accept uploads. A failure message is the end of the attempt. Sending the picture away would break the privacy line on this page.
Will the JPEG be as small as the AVIF?
Usually not. AVIF's whole point is that it spends fewer bytes. A JPEG at quality 92 is there so other software can open the picture. Lower the slider if you need a smaller attachment and can tolerate more compression. You will not get the AVIF's size back along with universal compatibility.
Does transparency survive?
Not in the JPEG. Transparent pixels are composited onto white. This site does not offer an AVIF to PNG page. If you need the alpha channel, use a desktop tool that writes PNG, or open the AVIF in a browser that can display it and export from an editor.
Is an animated AVIF converted to every frame?
No. You get one bitmap, the image the browser decoded. Image sequences and animation are not unpacked.