Image Format Converter
WebP, JPEG or PNG, with a quality slider for the lossy ones. Shows the output size so the trade-off is visible.
Result
Output
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Size vs original
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Worked example
WebP at quality 0.82 is typically 25–35% smaller than JPEG at the same visual quality. Below about quality 0.7, artefacts become visible on gradients and skin.
Format choice matters more than quality setting for most images. WebP wins on size for photographic content and supports transparency; PNG is for anything with sharp edges, text or few colours; JPEG is for photographs when compatibility with old software matters.
The transparency trap
JPEG has no alpha channel. Converting a transparent PNG to JPEG without filling the background first produces black where the transparency was — visible immediately on a dark page and invisible on a white one.