Convert JPG & PNG to WebP

WebP's quality scale is not directly comparable to JPEG's despite sharing the same 0–100 range and similar-sounding slider — WebP's prediction-based encoding holds up better at a given number than JPEG's does, so a WebP at quality 82 typically looks closer to a JPEG at quality 90 than to a JPEG at 82. In practice this means WebP images can be pushed a bit lower on the quality scale than the equivalent JPEG habit suggests, while still looking clean. Quality 82 is the point where the size saving is substantial and no compression artefact is visible on ordinary photographic content.

Pushing below roughly quality 70 starts to show the same category of artefact JPEG shows at low settings — blocky detail loss in busy areas and softening of fine texture — because both formats are ultimately trading detail for size, just at different rates. For most web use there is little reason to go that low: the difference between 82 and 70 is a modest further size saving for a real, visible quality cost.

Because this accepts mixed JPG and PNG input in one batch, a folder containing both photographs and PNG screenshots can be converted in a single pass — each source image keeps its own characteristics (a PNG with transparency keeps its alpha channel in the WebP output; a JPEG without transparency simply converts) rather than needing to be sorted by format first. This is the fastest route to converting an entire media library or a website's image folder over to WebP without touching each file's settings individually.