Unlike local government exams that restrict files to a tiny 20KB limit, international portals (such as the US DS-160, UK VFS, or Indian Passport Seva) employ highly advanced biometric matching algorithms.

These systems require high-resolution imagery (typically 600x600 pixels or higher) to accurately map facial geometry—measuring the exact distance between your eyes, the shape of your jawline, and the depth of your features. Heavy JPEG compression (under 50KB) introduces "artifacts" (pixelation) that warp these geometries and cause instant automated rejections.

By targeting a file size between 100KB and 300KB, you ensure that the image retains near-lossless clarity for biometric scanners while still falling under the maximum file upload limits set by embassy servers (which is often 240KB to 300KB).