Compress Signature Image to 20KB

Most Indian government and banking portals want the scanned signature between 10KB and 20KB in JPEG format. The 20KB target is pre-set — drop your scan, and if your portal wants it even smaller, just lower the target.

Last updated: August 2026

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A signature is the one image in an application where how you capture it decides almost everything that follows. Unlike a photograph, there is very little information in a signature — a few dark strokes on white — which means it compresses to a tiny file effortlessly, provided the capture is clean. Every problem people have hitting a 20KB target comes from what surrounds the ink rather than from the ink itself.

Consider what a phone photo of a signature on a desk actually contains: paper texture, the grain of the desk, a shadow from your hand, a slight colour cast from the room light, and somewhere in the middle, the signature. Compression has to encode all of it. Strip that away — plain white paper, even light, cropped tight to the strokes — and the same signature reaches 20KB while staying perfectly crisp, because there is almost nothing left to store.

And as with the photograph that accompanies it, the requirement is usually a range rather than a ceiling. A signature compressed to 4KB is commonly rejected by a portal asking for 10KB to 20KB, which is a genuinely confusing failure because the file looks fine and is comfortably "under the limit". Check your notification for both bounds before you compress.

How to compress a scanned signature to 20KB

1
Capture it properly
Sign in dark ink on plain white paper. Photograph or scan it straight on, in even light, with no shadow falling across the page. This step decides the outcome more than any setting does.
2
Crop tight to the strokes
Trim to just the signature with a small even margin. Every millimetre of paper you keep is background the compressor has to encode instead of ink.
3
Set the target inside the range
The 20KB target is pre-filled here. If your portal states a band such as 10KB to 20KB, aim near the middle rather than at either edge.
4
Check it is still legible
Open the result at full size. A signature has to be readable as a signature — if the strokes have broken up, the capture was the problem, not the compression.

Pro tip: If the scan has a grey or yellowish background, raise the contrast before compressing rather than compressing harder. A signature on genuinely white paper compresses to a fraction of the same signature on off-white paper, because a uniform white area costs almost nothing to store while a subtly varying one costs a great deal. Fixing the background is the difference between a clean 8KB file and a struggle to reach 20KB — and it also makes the signature look more like the ink-on-paper the portal expects.

Troubleshooting: If the portal rejects a signature that is well under the size limit, look for a minimum in the requirement — this catches almost everyone at least once. If you cannot get under the target at all, the capture has a background problem: shadows, desk texture or coloured paper. If the strokes look broken or speckled, the file was compressed too far for the amount of detail present; recapture on white paper and crop tighter instead of pushing the quality down.

The photograph that goes with it has its own preparation: Compress Photo for SSC and Compress Photo for UPSC cover the ranges and the other rules checked alongside them. If your portal names a smaller figure, Compress JPG to 10KB explains what is realistic at that size. For cropping the scan before compressing, Crop Screenshot Online works equally well on a scanned page, or use the full Compress Image tool.

Frequently asked questions

How do I compress a signature to 20KB?

Capture it on plain white paper in even light, crop tightly to the strokes, then compress with the target set to 20KB. The capture and the crop do most of the work — a clean signature reaches this size easily, while a photo of one on a desk struggles.

Why was my signature rejected for being too small?

Because the requirement is usually a range rather than a ceiling. A portal asking for 10KB to 20KB rejects a 4KB file just as it rejects a 40KB one. This is confusing precisely because the small file looks fine and appears to satisfy the limit.

Why does my signature file stay too large?

Almost always the background. Paper texture, desk grain, shadows and colour casts all have to be encoded alongside the ink, and they cost far more than the strokes do. Recapturing on plain white paper in even light usually solves it outright.

Should I scan my signature or photograph it?

Either works if the result is clean. A scanner gives even lighting and a flat page automatically. A phone photo can be just as good taken straight on in bright, even light with no shadow across the paper — the thing to avoid is a raking light that picks up texture.

Is my signature uploaded when I compress it?

No. Compression runs entirely inside your browser on your own device — the file is never uploaded, stored, or logged. For a specimen signature, which is exactly the kind of thing that should not travel to someone else's server, that matters.

Looking for the full-featured version? Open the main Compress Image tool.

Compress Signature Image to 20KB

How to compress a scanned signature to 20KB

Capture it properly

Crop tight to the strokes

Set the target inside the range

Check it is still legible

Frequently asked questions

How do I compress a signature to 20KB?

Why was my signature rejected for being too small?

Why does my signature file stay too large?

Should I scan my signature or photograph it?

Is my signature uploaded when I compress it?

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Compress JPG to 20KB – Free Online Tool