AVIF is the strongest still image compression widely available, and this is the conversion that demonstrates why. A JPEG re-encoded as AVIF typically lands at 40–60% of its original size while looking the same or better. If you are optimising a photo-heavy site and WebP has already been squeezed dry, AVIF is the next step.
It is slow, and here is why
AVIF encoding is genuinely expensive. It comes from AV1, a video codec designed on the assumption that encoding once and decoding millions of times is a good trade. Expect several seconds for a phone photo and appreciably longer for a large one, especially on a laptop or a phone. That is the encoder working, not the page hanging.
On top of that, the first conversion on this page downloads a 3.5 MB WebAssembly encoder, because no browser can produce AVIF on its own — they can all display it, but none can create it. That download happens once and is then cached by your browser, so subsequent files start immediately. It is also the reason this page is heavier than the other converters here, and why that encoder is not loaded on any page that does not need it.
Quality numbers do not map to JPEG
- AVIF quality 50 is roughly comparable to JPEG quality 75–80. Setting it to 90 because that is your JPEG habit will produce a file larger than the original for no visible benefit.
- Between 45 and 60 is where AVIF does its best work on photographs.
- Below 35, AVIF fails differently from JPEG: instead of blocky artifacts it smooths away fine texture, so skin and foliage start to look waxy.
Remember you are re-compressing
Your JPG has already discarded detail. AVIF is now compressing that damaged image, and it will faithfully preserve the JPEG artifacts it finds — sometimes spending bytes doing so. The best results come from converting an original camera file, not a JPEG that has already been through a messaging app twice. Keep the JPG; treat the AVIF as a delivery copy.
Before you deploy AVIF
Every current browser can display AVIF, but very little else can. Users who right-click and save an image will get a file their computer probably cannot open, and older browsers still in the field will show nothing at all. The standard practice is to serve AVIF inside a <picture> element with a JPEG or WebP fallback, so the browser picks what it can handle rather than being handed a format it cannot.
All encoding happens in a background thread in this tab, on your own machine, using a single-threaded build of the encoder specifically so the site does not need the security headers that would break in ordinary hosting. Your photographs are never transmitted.