What fits in 20 KB
- A head-and-shoulders photo: in our test it came out at 435 × 435 pixels. The face was clear; fine detail like fabric texture was soft.
- A signature: easily, if the background is clean. Use the signature tool, which whitens the paper and crops to the ink first.
- A full page of a document: no. In our test, a phone photo of a typed page couldn't get under 20 KB and stay readable. Use a PDF box if the form has one.
How we tested: a 512 × 512 head-and-shoulders portrait (a public-domain NASA photo) and a 12-megapixel phone photo of an A4 page of 11-point typed text, run through this tool with its default settings in Firefox. Busy backgrounds and noisy low-light photos need more space.
Tips for a 20 KB limit
- Crop first. Cut the photo down to just the face, or just the signature. Every pixel of background costs space.
- Use a plain, light background. Shadows, patterns and noise from dim light take far more space than a smooth wall.
- If the form gives pixel dimensions, enter the largest side so the tool doesn't spend the 20 KB on pixels the form will throw away.
Questions
The form also says "minimum 10 KB". Will the file be too small?
The tool uses the best quality that fits under 20 KB, so the result is usually close to 20 KB. Check the size shown before you upload.
Why did it say it couldn't get under 20 KB?
The tool stops before an image gets so small it would be useless. Crop the photo more tightly, or use a cleaner photo, and try again.
Last updated 2026-10-23.