Compress an image to 20 KB

What 20 KB is used for

A 20 KB limit usually means the form wants a signature, a thumb impression or a very small ID photo. It sounds tiny, but a signature is simple black lines on white, which compresses extremely well. A clean signature scan around 400 pixels wide fits under 20 KB with sharp edges. The trouble only comes from scanning or photographing the whole page and uploading that.

Preparing a signature for a 20 KB limit

1. Sign on plain white paper with a dark pen. Blue or black both work.
2. Photograph or scan it in good light, straight on, so the paper looks white rather than grey.
3. Crop tightly around the signature with the crop tool, leaving a small margin.
4. If the form gives dimensions, such as 140 by 60 pixels, resize to exactly that.
5. Compress here. The target is already 20 KB.

Grey paper and shadows are the main reason signatures look muddy at small sizes: the compressor spends its budget on uneven background instead of the ink. Good light fixes more than any setting.

Small photos at 20 KB

For a small face photo, crop to the head and shoulders and keep the dimensions modest, around 200 to 300 pixels wide. At that size a 20 KB JPG looks clean. If the tool has to reduce the dimensions to fit, the result will note the final size, and you can check it against what the form requires.

If the form still says the file is too big

This tool counts 20 KB as 20,000 bytes, the strictest reading, so the size itself will pass. If the form still rejects the file, check its other rules: the file type (most want .jpg), the pixel dimensions, and sometimes a minimum size as well as a maximum.