How to Compress a PDF to Under 200 KB, 500 KB or 1 MB for Online Forms
2 Oct 2026 · 2 min read · PDF tools
Online forms often limit uploads to 200 KB, 500 KB or 1 MB, while a scanned certificate from your phone can easily be 5 MB. Here is how to shrink it without making it unreadable.
Why are scanned PDFs so big?
A scanned PDF is really a set of photos. A modern phone photo has 12+ megapixels — far more detail than a printed page needs. Compressing reduces that detail to what is still easy to read.
Step by step
- Open Compress PDF and choose your file.
- Pick a compression level. Start with the recommended level and check the result size.
- If it's still too big, choose stronger compression.
- Open the downloaded file and zoom in to make sure the text is still readable.
If it is still too big
- Convert to black and white. Colour pages are about three times larger. Grayscale PDF often halves the size of a scanned document.
- Remove extra pages. Upload only the pages that are asked for — use Split PDF to keep just those.
- Rebuild from photos. If you have the original photos, crop them tightly and use JPG to PDF — cropping away the table and background makes a big difference.
Quick guide by target size
| Target | What usually works |
|---|---|
| Under 1 MB | Recommended compression is enough for most 1–5 page scans |
| Under 500 KB | Strong compression, or grayscale + recommended |
| Under 200 KB | Grayscale + strong compression, one or two pages only |
Combining several documents
Some forms want all certificates in one PDF. Compress each file, then join them with Merge PDF, and check the final size.
Privacy
Your PDF is compressed in your browser. Mark sheets, ID cards and bank statements never leave your device.