Worth knowing before you start
Signatures fail on size, not on looks. A signature that looks fine on screen still gets rejected if it is 21KB against a 20KB limit. Check your notification for the exact number first — the current limits live in our exam photo and signature size guide.
Contrast is everything. Scanners capture paper texture as grey noise, which costs bytes and looks blotchy. Push the contrast before compressing — clean white background, dark ink — and the file shrinks dramatically while looking sharper.
Crop ruthlessly. A signature surrounded by empty paper is paying bytes for nothing. Crop tight to the ink before you compress; it is the easiest size win there is.
Make a compliant signature in four steps
1. Scan or photograph cleanly
Sign with dark ink on plain white paper, in good light. Avoid shadows and ruled lines — every speck of grey becomes bytes you have to squeeze out later.
2. Crop to the ink
Cut away all empty paper around the signature. A tight crop can halve the file size before compression even starts.
3. Compress to the target
Open the SizeMint compressor, enter the exact KB limit from your notification, and choose JPG unless the form names another format. Processing happens entirely in your browser — your signature never leaves your device.
4. Verify before uploading
Check the file size in your file manager and view the signature at full size. Ink should be dark and edges clean. Keep the original scan.
JPG or PNG for signatures?
Use the format the form names — full stop. If it does not name one, JPG compresses scanned ink far smaller than PNG, because PNG's lossless encoding wastes bytes on paper grain. PNG only makes sense if the portal explicitly asks for it. For the general trade-offs, see our WebP vs JPG comparison.
Common signature failures
Grey, blotchy background: raise contrast before compressing, or re-scan with better light. Do not try to fix it with heavier compression — that just bakes the blotches in.
File still too big: you probably did not crop tight enough, or the scan resolution is huge. A signature needs a few hundred pixels of width, not a few thousand.
Rejected despite correct size: check the format and dimensions too — some portals validate those alongside the byte count.
Questions, answered
What size should my signature be for SSC and IBPS forms?
Signature limits are usually tighter than photo limits — commonly 10–20KB on SSC and IBPS style portals. Always check your specific notification; limits change between exams.
Should a signature be JPG or PNG?
Use the format the form names. JPG compresses far smaller for scanned ink; PNG only makes sense if the portal explicitly asks for it.
Why does my scanned signature look grey and blotchy?
Scanners capture paper texture as grey noise. Increase contrast before compressing — clean white background, dark ink — and the file shrinks while looking sharper.
Can I compress my signature without uploading it?
Yes. SizeMint processes the image entirely in your browser — the signature never leaves your device.
Use the compressor
Ready? Open the SizeMint compressor, enter your signature's KB limit, and download your file.