When JPEG is the right output
If the picture has sky, skin, fabric, or a busy street, JPEG (or WebP) will beat PNG by a wide margin. A 12 megapixel export from a phone is often 4–8 MB because the default quality is “almost a negative.” Web pages do not need that. A 1600-pixel-wide JPEG at quality 80 is usually a few hundred kilobytes and still looks like the same evening.
Set a target like 200 KB if an upload form refuses larger files. The tool lowers quality, then if it must, scales the pixel dimensions. That second step is visible on tiny text in the frame — another reason not to JPEG a screenshot of a UI.
What we do not claim
We do not run TinyPNG’s proprietary quantizer. We use the browser’s JPEG encoder. On Chrome that is a solid, boring encoder. The win is privacy and batch, not a magic extra 8% versus Squoosh’s MozJPEG. If you need MozJPEG, use Squoosh on one file. If you need twenty product shots out the door without an upload, stay here.
Related: quality 80 explained · try WebP · all formats