20 KB: protect thin lines before chasing the last byte
Start with a crop that contains only what the destination needs. A large margin around a small drawing consumes pixels without making the drawing easier to read. ExactKB keeps the input proportions: it does not find a signature, remove a background or crop a scan for you.
For a clean line drawing, compare PNG and JPG rather than assuming the photo format wins. PNG can retain crisp edges and transparency. A busy scan or photograph may fit more readily as JPG, but a 20 KB budget can force either a smaller image or visible artifacts. The measured scan below contains invented lettering and a test stroke, not a real signature.
Measured 20 KB examples
Measured with the actual ExactKB compressor in Chrome 155.0.8059.84 on macOS, using decimal units, automatic dimensions and no size preset. Encoder percentages are settings, not measured detail retention. Results vary with the image and browser. Files are synthetic, contain no customer images, and are available below so you can reproduce the comparison.
The textured PNG input is 3,031,966 bytes at 1200×900. Download the textured original. The line-scan original is 52,556 bytes at 1200×500. Download the scan original.
On a narrow screen, scroll the results table sideways to see all columns.
| Input / target | Output bytes | Output pixels | Encoder setting | Inspect file |
|---|---|---|---|---|
| Texture / 20 decimal KB / JPG | 19,894 | 653×490 | 62% | Download output |
| Line scan / 20 decimal KB / JPG | 19,837 | 876×365 | 79% | Download output |
| Line scan / 20 decimal KB / PNG | 14,961 | 330×137 | Not applicable | Download output |
To reproduce: upload the matching original above, choose the target shown in the row (this page starts at 20 KB), turn off the 1024-byte option, leave Longest side on Automatic and select the table’s output format. Press Compress and compare exact bytes and dimensions. The decimal ceiling is 20,000 bytes; leaving binary units enabled instead permits 20,480 bytes.
If 20 KB fits but the upload still fails
Check minimum dimensions first. In our textured test, a 1200×900 input became 653×490. A destination requiring at least 600 pixels on each side would reject that result despite its valid byte count. A 600 px maximum-side preset cannot fix this: it limits the longest side rather than guaranteeing either minimum. If your required crop cannot remain legible inside the permitted range, use a better source or ask the destination for its supported alternative.
Before using the download
If the result says “Could not fit”, its download is an above-limit best effort, not a successful compression. Do not upload it as a file that meets your cap. Try a larger permitted budget or prepare a simpler crop from the original.
Open the downloaded result and inspect the detail your task requires. Confirm format, actual bytes and both dimensions against the destination’s current instructions. A successful size badge does not validate composition or a separate minimum file size.
Compare 50 KB · How quality and dimensions are chosen · Troubleshoot a rejected upload