JPG to AVIF Converter

AVIF stores photos in noticeably fewer bytes than JPG and even WebP, and every current browser displays it. Browsers cannot save AVIF from a canvas, so this converter encodes each picture with the browser's own AV1 video encoder (WebCodecs) as a single still frame and writes a standard AVIF file around it — all on your device. Chrome and Edge on computers have that encoder; in a browser without one, the page tells you instead of producing a broken file.

How to use this tool

1. Drop one or more JPG files (PNG and WebP work too).
2. Set the quality: 50–70 is typical for web photos.
3. Optionally set a max size, then convert.
4. Compare the size change and download the AVIF files.

Formula

AV1 quantizer = round((100 − quality) × 63 ÷ 100), from 0 (best) to 63 (smallest). Size change = (AVIF bytes ÷ JPG bytes − 1) × 100%.

Pixels are converted to YCbCr 4:2:0 with the BT.601 matrix in full range (as JPEG does) and labelled nclx 1/13/6 so decoders restore sRGB colours. The file holds ftyp (avif, mif1, miaf), a meta box with the item, its size (ispe), AV1 configuration (av1C), bit depth (pixi) and colour (colr), and the AV1 data in mdat. Transparent PNGs get a second AV1 image as an alpha layer. EXIF metadata is not copied.

Example

At the default quality 60 the quantizer is round(40 × 63 ÷ 100) = 25. If a 500 KB photo becomes a 180 KB AVIF, the size change is 180 ÷ 500 − 1 = −64%, shown under the file; the actual saving depends on the picture and on how strongly the JPG was already compressed.