An upload form says “file too large” and refuses your PDF. Many portals accept only 1 to 5 MB, and a scanned document can easily be several times that. This guide shows how to compress a PDF in your browser, which level to try first, and how to check that the result is still readable before you submit it.
Step 1: Check the Limit and Your File Size
Read the size limit next to the upload button. Then check your file size in your file manager. PaperDesk also shows the size of the selected file in KB, so you can compare it with the limit. If your file is already under the limit, you do not need to compress it.
Step 2: Compress With the Recommended Level
- Open Compress PDF.
- Click “Choose PDF File” and select your document.
- Leave the level on “Recommended — Balanced”.
- Click “Compress PDF” and wait while each page is processed.
- A file named paperdesk-compressed.pdf downloads, and a message under the button tells you how much smaller it became.
My Test
I tested the tool with a practice PDF of 6,789.4 KB made of photo-style scanned pages. With the Recommended level, the tool reported that the size was reduced by 92.0%, and the downloaded file was 541 KB. That is far below a typical 1 MB to 5 MB form limit. Results depend on the file, so a PDF with fewer images may shrink much less.
Step 3: Use High Compression Only If Needed
If the file is still above the limit, run the original file again with “High Compression — Smaller File”. It gives a smaller result, but pages can look softer, so small print may be harder to read. Always start from your original file, not from an already compressed copy.
Step 4: Check the Result
- Open the new file and scroll through every page.
- Zoom in on stamps, signatures and small text.
- Compare the new size with the upload limit.
- Keep your original file until the upload is accepted.
What to Know Before You Compress
PaperDesk turns each page into a compressed image and builds a new PDF from those images. This suits scans and photo-heavy files. The text in the new file cannot be selected or searched. A PDF that is mostly typed text may not get smaller, and the tool will say so.
If It Is Still Too Large
- Send fewer pages. Use Split PDF to keep only the pages the form needs.
- Rebuild the file from smaller photos with Image to PDF.
- Split a long document into parts and upload them one by one. See our guide on splitting a PDF into parts.
Common Questions
Does compressing change my original file?
No. A new file is created and your original stays as it is.
Are my files uploaded to a server?
No. Compression happens inside your browser. See our Privacy Policy.
Related Guides
How to Reduce PDF Size for Email and Online Forms, How to Extract a Single Page from a Large PDF and How to Turn Photos of Notes into One PDF for Assignments.