500 KB is generous: it is used for document uploads, higher-resolution photos and some visa portals. Most photos only need their pixel size reduced from phone resolution to get under it, with almost no visible loss. If you are combining several scans, image to PDF can build one file under 500 KB. For very large images the tool reduces pixels only when quality alone isn't enough.

New to KB limits? Read the full guide on the compress to 50 KB page: how the compression works, 1,000 vs 1,024 bytes, min–max ranges and keeping photos sharp.