PNG to AVIF Converter

AVIF compresses graphics, screenshots and photos far better than PNG while still supporting transparency, and all current browsers display it. Browsers cannot save AVIF from a canvas, so this converter encodes each picture with the browser's own AV1 encoder (WebCodecs) and writes the AVIF file itself. Transparent PNGs keep their transparency as a separate alpha layer, as the AVIF standard defines; or you can fill it with white or black. It runs in Chrome and Edge on computers.

How to use this tool

1. Drop one or more PNG files.
2. Set the quality; 70 is a good start for logos and screenshots.
3. Keep transparency, or fill it with white or black; optionally set a max size.
4. Convert, check the size change and download the AVIF files.

Formula

AV1 quantizer = round((100 − quality) × 63 ÷ 100). The alpha layer is encoded at quality ≥ 90 so edges stay clean. Size change = (AVIF bytes ÷ PNG bytes − 1) × 100%.

Colour is converted to YCbCr 4:2:0 (BT.601, full range) and labelled nclx 1/13/6. The alpha channel becomes a second AV1 image whose brightness is the opacity, marked as an auxiliary item of type urn:mpeg:mpegB:cicp:systems:auxiliary:alpha and linked to the colour image with an auxl reference — the standard AVIF alpha layout that browsers and libavif read. AVIF is lossy here: use PNG or lossless WebP where every pixel must stay exact.

Example

At quality 70 the AV1 quantizer is round(30 × 63 ÷ 100) = 19. If a 420 KB transparent PNG becomes a 63 KB AVIF, the size change is 63 ÷ 420 − 1 = −85%, shown under the file; the exact saving depends on the picture.