JPG to AVIF converter

AVIF compresses better than anything else in general use — commonly half the size of JPEG at the same perceived quality, and it holds up much better at aggressive settings, where JPEG turns blocky and AVIF just softens. If you are shrinking a large library of photographs for the web, or archiving them where storage costs something, this is the conversion with the most to gain. The price is encoding time, and it is not small.

When you actually need this conversion

• You are optimising a photo-heavy site and have already taken WebP as far as it goes.
• You are archiving a large collection where halving the total size is worth waiting for.
• You need quality to survive heavy compression — AVIF degrades far more gracefully than JPEG at low bitrates.

What to watch out for

• Encoding is slow. A large photograph can take several seconds, and a big batch is a job you start and walk away from. Decoding, by contrast, is fast.
• Software support outside browsers is still thin. Treat AVIF as a delivery and archive format, not as something to email to a colleague.
• Re-encoding an already-lossy JPEG loses a little more. Start from the best original you have.

JPG and AVIF, side by side

The most aggressive size reduction available for web images — often half the bytes of the JPEG at the same perceived quality. Encoding is slow, sometimes several seconds for a large photograph, because AV1 searches a very large space of prediction modes.

How the conversion works here

Your file is decoded in a Web Worker inside this browser tab — by the browser's own image pipeline where it can, and by a WebAssembly build of libheif or libavif where it cannot. The decoded pixels are then re-encoded with libavif, the same encoder Squoosh uses.

All of that happens on the processor in front of you. There is no upload step, no queue and no server, which is why there is no size cap, no daily allowance and no paid tier — and why the whole thing keeps working with the network switched off.

Doing more than one thing

Most people converting a format also need it smaller or a different size. The result screen hands your converted files straight to the compressor or the resizer in one click — no second download, no re-selecting files. If you need several formats, the general converter lets you pick the output each time.