Compress an Image to 20KB

20KB is one of the tightest limits you will meet. It is common for scanned signatures and small ID photos on exam, scholarship and government application forms. At that size every pixel counts, so the order of the steps matters.

For a signature

  1. Sign in dark ink on plain white paper.
  2. Photograph it in daylight, straight on, with no shadow across the page.
  3. Crop tightly around the signature in the image cropper with the Free ratio - empty paper still costs bytes.
  4. Open the image compressor, choose Target Size (KB), type 20 (or 18 for a margin) and click Compress Image.
  5. Download the JPG.

Open the image compressor →  ·  Open the image cropper →

For a photo

A photo at 20KB has to be small in pixel terms - roughly thumbnail size. Crop to head and shoulders with the Passport 2x3 preset first, then compress with a target of 20. Expect the tool to reduce resolution as well as quality; that is how it guarantees the limit.

Why signatures compress so well

A signature is mostly flat white with thin dark lines, which leaves very little detail for the encoder to store. A clean, evenly lit shot can stay crisp well under 20KB, while a shadowy photo of the same signature carries noise that eats the budget. Good light matters more than any setting.

Frequently asked questions

How can I compress a signature to 20KB?

Crop tightly around the signature, then use Target Size (KB) mode with 20. The result is guaranteed to be under 20KB.

My photo looks blurry at 20KB - what can I do?

Crop tighter so fewer pixels have to fit, and check whether the form allows a bigger limit such as 50KB. At 20KB some softness in a photo is unavoidable.

Does it work on my phone?

Yes. Everything runs in your mobile browser and nothing is uploaded.

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