How to Convert JPG to AVIF in Your Browser

How JPG becomes AVIF

1. The browser’s JPEG decoder unpacks the DCT-compressed image data into a full grid of pixel values, the same step needed just to display the photo.
2. That pixel grid is drawn onto a canvas — JPEG has no alpha channel, so there’s no transparency to carry through this step, only opaque color data.
3. The canvas is encoded as AVIF using the browser’s AV1-based image encoder at your chosen quality setting, a second lossy compression pass layered on top of the JPEG that already happened.
4. The resulting blob’s MIME type is checked to confirm it’s genuinely image/avif before the download is offered, so you never get a mislabeled file if encoding quietly fails.

What changes when you convert

You’re stacking two lossy codecs. AVIF’s encoder works only with the pixels JPEG’s decoder already reconstructed, so it can’t recover detail JPEG compression discarded when the photo was first saved — a higher AVIF quality setting keeps more of what’s currently there, not more of the original scene.

File size typically shrinks, since AV1-based compression is generally more efficient than JPEG’s at comparable visual quality — but that’s a tendency, not a guarantee. Highly compressed or low-detail JPGs sometimes don’t shrink much further.

Nothing changes regarding transparency: JPG never had an alpha channel, so the AVIF output is fully opaque, the same as the source. Dimensions and any orientation applied during decode carry through, but EXIF metadata itself is not copied into the AVIF.

When AVIF is the right choice — and when it isn’t

Converting makes sense when you’re preparing images for a site or app you know serves AVIF to modern browsers and want the smaller file size AVIF typically delivers for photographic content — a product gallery or blog with many large JPGs is a good candidate.

It’s not worth it for a one-off photo headed to email, an older device, or software you don’t control, where AVIF might simply fail to open. It’s also not the move if you’re hoping for a quality upgrade — re-encoding a JPG as AVIF cannot undo compression artifacts the JPEG already introduced; if that’s the concern, you’d need the original uncompressed source instead.

Limitations and privacy

AVIF encoding is Chromium-first: current Chrome, Edge, and similar browsers can produce it via canvas, but some others can’t yet, even though they may be able to open an existing AVIF file. On unsupported browsers, the tool shows a clear compatibility error instead of quietly saving something else with an .avif extension.

The quality slider runs 50–100% and defaults to 90%; there’s no lossless AVIF mode here. Everything happens locally — the JPG is decoded, redrawn, and encoded entirely in your browser, with no upload to a Looty Tools server.