High quality with a size cap
500 KB is a generous limit. It keeps photos sharp enough to zoom in a little, to print at small sizes and to use as website banners, while still being a fraction of a typical 3–8 MB phone photo. The tool tries several compression levels and picks the best one that stays under the limit.
Common places that ask for files under 500 KB include school and university applications, government portals, online shops and email newsletters.
Getting the most out of 500 KB
If you control the dimensions, resizing a huge photo to around 2000 pixels on the long side before compressing leaves more of the 500 KB budget for detail. For website images, WebP gives the same quality at a smaller size than JPG.