Compress an image to 20 KB
20 KB is a signature-sized budget, not a picture-sized one. Almost every request for it comes from the same place: the signature box on an examination, banking or government application form, which typically wants a scanned signature as a JPG somewhere between 10 KB and 20 KB. Those forms ask for a small file because a signature is a few strokes of dark ink on white paper, and that compresses to almost nothing.
It matters which of those two things you have. A scanned signature at 20 KB looks essentially perfect. A picture at 20 KB does not — there is no encoder that fits a face, a background and a scene into twenty thousand bytes without either dropping the dimensions hard or visibly breaking the image up. If a form asked you for a 20 KB picture, check it again; it is far more often a 20 KB signature next to a 50 KB portrait.
If it is a signature
Crop it tight first. A signature scanned on A4 is mostly empty paper, and empty paper still costs bytes and still forces the encoder to shrink the whole page to fit your target — including the part you actually need. Cropping to the ink alone will often get you under 20 KB before any compression is needed at all.
Then check whether the form also specified pixel dimensions. Most do: 140 × 60 px is the most common signature box, and a file that is the right size but the wrong shape gets rejected just as firmly as one that is too big. The signature resizer sets both at once and defaults to exactly that.
Keep it as a JPG unless the form says PNG. A signature is mostly flat white, which JPEG handles efficiently, and PNG cannot be pushed toward a byte target the same way — see below.
If it really is a picture
Leave “Allow resizing” switched on. At 20 KB, quality alone will not get a normal picture there, and the search will need to reduce the dimensions — often a lot. That is the honest trade at this size and the tool will tell you exactly how far it went.
Crop before you compress. Every pixel you remove is quality you get to keep in the pixels that remain, and at a target this tight the difference is not subtle.
If the result comes back visibly broken up, the target is genuinely too small for that picture rather than the tool giving up early. Image KB Reducer will hand you the smallest file it did manage and tell you what it was, so you can decide whether to raise the target or crop harder.
Why a PNG will struggle here
PNG is lossless, so there is no quality dial to turn down — the browser ignores the quality setting for PNG entirely. Image KB Reducer optimises the PNG losslessly first and reduces dimensions only if that is not enough, which at 20 KB it usually is not.
A scanned signature saved as PNG is one of the few cases where this works out, because a two-colour image compresses extremely well losslessly. A picture saved as PNG at 20 KB does not; convert it to JPG first and you will get a far better-looking result at the same size.
Questions about 20 KB
Why does my picture look so bad at 20 KB?
Because 20 KB is roughly a hundredth of what a phone snapshot normally takes. At that budget the encoder has to either throw away most of the detail or most of the pixels. It is not the tool giving up — it is the size being genuinely small for a picture. Cropping tightly before compressing helps more than any setting.
My form wants 10 KB to 20 KB for a signature. Which should I aim for?
Set the target to 20 KB. Image KB Reducer never returns a file over your target, so anything it gives you is inside a 10–20 KB range's upper bound, and aiming at the top of the range keeps the most quality. If the form insists on a minimum too, check the result — a very clean signature can come out well under 10 KB, in which case scan or export it at slightly larger dimensions.
Should the signature be JPG or PNG?
JPG, unless the form specifically asks for PNG. Most Indian examination and banking portals ask for JPG or JPEG for both portrait and signature. JPG also gives Image KB Reducer a quality dial to work with, which PNG does not.
Can I get exactly 20.0 KB?
No, and no honest tool can. Encoders do not take a byte count as an input — you set a quality and find out the size afterwards. Image KB Reducer searches for the highest quality that lands at or under 20 KB, so you might get 19.4 KB or 17.8 KB depending on the image. It will never go over.
Tools that help at this size
- Signature Resizer
Defaults to 140 × 60 px at a 20 KB target — the combination most forms ask for, set in one step.
- Crop
Cut the empty paper off a scanned signature before compressing. Usually the only step needed.
- Image Info
Check the dimensions and format of what you have before deciding what to change.
Other exact sizes
Each of these is a different page about a different size, because different things ask for them. If none of them is your number, set any target you like.