Why pixel size and KB limit both matter
Passport, visa, exam and signature uploads almost always state two separate requirements: exact pixel dimensions (so the photo prints or displays correctly) and a maximum file size in KB (so their system accepts the upload). Hitting only one isn't enough - resize to the wrong file size and a portal will reject it even if the dimensions are perfect. This tool does both in one pass: crop, resize to the exact pixels, then compress down to the size cap.
Always double-check against your actual form
The presets here reflect commonly published, typical requirements - but passport offices, embassies and exam boards do change their specs, and some ask for things a generic tool can't verify (a plain white background, no smiling, no glasses). Use "Custom" if your form states different numbers, and treat any preset as a strong starting point, not an official guarantee.
Signatures
For a signature, sign in dark ink on plain white paper, photograph it in even light, then crop tightly before picking the signature preset (or custom dimensions) - a clean, high-contrast source compresses much smaller than a shadowy phone photo.