Passport upload forms reject photos for two reasons and they are both easy to avoid. The first is framing: the printed photo must be 2 x 2 inches (51 x 51 mm) and the head, chin to top of head, must land between 1 inch and 1 3/8 inches (25 - 35 mm) inside that square. The second is authenticity: the State Department asks for the original, unedited photo, without filters or digital changes. That second rule is why the compression step matters. A phone photo straight off the camera is often 4 to 8 MB, which is more than many upload forms will take and far more than the print needs. Recompressing to a sane byte size changes no framing, no background, no facial feature — it just removes bytes the printer never needed. What does break a photo is cropping the head wrong, whitening the background, or running a filter. So: crop to the square with the head sized correctly, then compress. Skwish resizes to exact dimensions and compresses to a KB target in the browser, shows the before and after size per file, and never uploads anything to a server. GOV.UK's own digital-photo rule is a useful sanity check for any upload: at least 600 x 750 pixels, at least 50KB and no more than 10MB.