Convert images in bulk

Choosing the right format

Converting an image is not a neutral act. Every format makes different assumptions about what is in the picture, and picking the wrong one can bloat a file or visibly damage it.

JPEG

JPEG assumes continuous-tone photographic content. It is universally supported and, for photos, still perfectly respectable. Its two hard limits: no transparency, and no lossless mode worth speaking of. It also struggles badly with sharp edges — which is why text and diagrams come out looking grubby.

PNG

PNG is lossless and supports full alpha transparency. It is the correct choice for screenshots, UI mockups, logos, charts and anything containing text. The trade-off is size: a PNG photograph can easily be five to ten times larger than the same image as JPEG.

WebP

WebP does both jobs. It offers lossy compression that typically beats JPEG by 25–35% at matched visual quality, plus a lossless mode that usually beats PNG, plus transparency and animation. Support is now universal across current browsers. For most web work it is the sensible default.

AVIF

AVIF is built on the AV1 video codec and is the compression champion — often around 50% smaller than JPEG at comparable quality. The catch is encoding cost: AVIF is significantly slower to produce, and not every browser can encode it yet. If the option is greyed out here, your browser cannot write AVIF; it can still read it.

A practical decision table

A note about transparency

Converting a transparent PNG to JPEG cannot preserve the alpha channel, because JPEG has no concept of transparency. The transparent areas have to become something — typically white or black. If transparency matters, convert to WebP or keep PNG instead.