A 20 KB limit usually means the form expects a single small page, such as a signature, a thumb impression or a one-page declaration. This page is pre-set to 20 KB and picks the clearest result that fits.
Tips for the best result
- Only one page will realistically fit. Use Extract pages to keep just the page you need.
- Always tick Convert to black & white — colour almost never fits in 20 KB.
- If the form accepts JPG, a cropped photo of your signature is often clearer than a PDF at this size.
How to compress PDF to 20 KB
- Select or drop your PDF (you can add several).
- Pick a compression level — or choose Exact size and type the limit, e.g. 200 KB.
- Click Compress PDF.
- Download the smaller PDF. We show you exactly how much space you saved.
Why use PDFNest to compress PDF to 20 KB
- Hit an exact sizeType 100 KB, 200 KB or 1 MB and we find the best quality that fits.
- See your savingsBefore and after size is shown, so you know it worked.
- Black & white optionTurn colour scans into grayscale for even smaller files.
- Stays on your deviceCompression runs in your browser — your PDF is never uploaded.
Frequently asked questions
How do I make a PDF smaller than 20 KB?
Keep only the page you need, add it here, tick black & white and click Compress PDF. The 20 KB limit is already set.
Why can't my PDF get under 20 KB?
Multi-page or colour scans contain too much detail for 20 KB. Reduce it to one page and use black & white; if it still doesn't fit, check whether the form allows 50 or 100 KB.
How do I reduce a PDF to 200 KB (or 100 KB)?
Add your PDF, choose "Exact size (KB / MB)", type 200 (or 100) and click Compress PDF. The tool tries different quality settings and gives you the best-looking version that fits under your limit.
Which compression level should I choose?
Recommended works for most files. Choose Extreme if you need the smallest possible size, Light if you must keep text selectable (for example a contract), or Exact size when a website gives you a maximum file size.
Why can't I select text after compressing?
The Recommended, Extreme and Exact size levels save each page as an optimised image — that's what makes scans and photos so much smaller. If you need selectable text, use the Light level.
Step-by-step guide: How to reduce PDF size for online forms (100 KB, 200 KB and more)
Read the guide