Scan on white paper
A signature on plain white paper compresses far better than one on lined or coloured paper, because there is less detail to store.
Signature resizer in KB
Scanned signatures come off a phone at two or three megabytes, and almost every form wants them in kilobytes at a fixed pixel size. Set both here and download a clean JPG — the file never leaves this browser tab.
Common signature targets
Crop tight, then resize
Trim the empty margins first. A tight crop keeps the strokes thick and readable even at 10 KB.
Check the pixel rule too
Portals usually state both a KB cap and a pixel box, often around a 3:1 or 4:1 strip. Match both before uploading.