What fits into 20KB
Twenty kilobytes is very little for a photograph. In our tests, a 2400 × 1602 landscape photo came out at 539 × 360 pixels and 19 KB, and a large portrait at 390 × 585 pixels. That is plenty for a form that shows the picture at thumbnail size, but it is not a file to print or zoom into.
Signatures are different. Dark ink on white paper is mostly flat color, which JPG stores efficiently, so a scanned signature 1500 pixels wide still came out at 1423 × 474 pixels within 19 KB. Simple, high-contrast images always survive a small limit better than detailed photos.
How to compress an image to 20KB
Start with the file the form will see. If the notice names a pixel size, resize to it first; if it only gives a file size, you can drop the photo or scan here straight away. The 20KB target is already selected, so the image is compressed the moment it is added.
Check the result line: it shows the new size in KB and, if the picture had to be reduced, its new width and height. Press Compare to see the original and the compressed version side by side, then download the JPG. To compress image to 20KB in bulk, add several files at once and save them all as one ZIP.
Signatures between 10KB and 20KB
Recruitment notices from IBPS, for example, ask candidates to sign on white paper with a black ink pen, scan the signature at 200 dpi or more, and upload it as a JPG between 10KB and 20KB. Other exam and job portals use similar rules, so read the notice for your application before you start.
Crop the scan close to the signature before compressing, leaving a small white margin. Empty paper still costs bytes, and a tight crop keeps the ink large and legible after compression. Use a pen with a fine to medium tip; very thin strokes fade when the file is squeezed.
When the result is below a minimum size
Some forms set a floor as well as a ceiling, such as at least 10KB. If your signature comes out smaller than that, the picture is too small or too simple, not too compressed. Make it larger first: the free image resizer can enlarge a signature to 600 or 800 pixels wide, and compressing that version lands higher inside the allowed range.
A file that is already under 20KB is left untouched and marked as kept, because compressing it again would only lose quality. That is the right outcome when the form accepts it as it is.
Resize to the required pixels first
Many forms name a pixel size as well, such as 200 × 230 for a photo. Resizing to exactly that size before compressing gives the best result, because the small file then only has to hold the pixels the form asks for, at a higher quality than an automatic reduction would pick.
Use the image resizer with an exact width and height and Crop to fill, choose which part to keep, then drop the resized file here. At 200 × 230 pixels a photo usually fits well under 20KB without visible blocks.
Scanning or photographing a signature
A flatbed scanner gives the cleanest result, but a phone photo works if you take care. Lay the paper flat in daylight, avoid shadows from your hand or the phone, and hold the camera straight above the page so the signature is not stretched or slanted.
Before compressing, crop away the desk, the edges of the paper and anything else in the frame. A clean white background compresses much better than a grey, shadowed one, so brighter light also means a smaller file.
How the compressor reaches 20KB
For JPG output the tool first tries a quality of 92 percent. If the file is still over 20KB, it searches downward for the highest quality that fits, and it normally stops lowering quality at 50 percent, below which blocky artifacts start to show. When even that is too big, it scales the picture down step by step and tries again.
The result line shows the new file size and, when the image had to be reduced, its new width and height. Sizes are counted in thousands of bytes, so a file under 20KB passes forms that count 1,000 bytes per kilobyte and those that count 1,024.
Checking the file before you upload
Open the compressed file and look at it at full size. The name should end in .jpg, the size should be under the limit, and a signature should read clearly without grey blocks around the strokes. Press Compare to slide between the original and the compressed version.
If an upload form still rejects the file, the reason is usually its format or pixel size rather than its weight. Photos from iPhones are HEIC; this page converts them to JPG automatically, and the notice for your form lists the exact dimensions it expects.
Private documents stay on your device
Signatures and identity photos are sensitive, so this compressor never uploads them. The file is read, compressed and saved by your own browser, and the page keeps working even if your connection drops after it has loaded.
The compressed JPG is written without EXIF data, which removes the camera model and any GPS location that a phone photo might carry.