How to compress a PDF to under 100 KB for online application forms
2026-10-27
Many online application portals, such as those for government jobs, entrance exams and scholarships, only accept PDF files below a size limit. Common limits are 100 KB, 200 KB or 300 KB. If your scanned certificate is 2 MB, the upload simply fails. This guide shows how to get under the limit while keeping the document readable.
Why scanned PDFs are so big
A scanned page is a photo. Phone cameras and scanners save these photos at high resolution, often 3000 pixels or more across, which is far more detail than a form reviewer needs. A single page can easily be 1 to 3 MB. Text-only PDFs made from Word are usually tiny already.
Steps to compress your PDF
- Open Compress PDF.
- Select your PDF file.
- Choose Recommended compression first and click Compress PDF.
- Check the size shown under the download button.
- If it is still above the limit, run the tool again with Extreme compression.
Always open the compressed file and zoom in before uploading. Make sure names, numbers and stamps are still clear.
Tips if the file is still too large
- Remove extra pages. A blank back side of a certificate doubles the size. Use Remove pages to delete it.
- Upload one document per file. If the portal asks for separate files, use Split PDF instead of uploading everything together.
- Scan in black and white or greyscale when colour isn't needed. Colour pages are much bigger.
- Crop the edges. Large dark borders from a scanner waste space. Crop PDF trims them.
- Start from a smaller photo. If you are converting photos with JPG to PDF, use your phone's "medium" or "low" photo size.
Is compression safe for official documents?
Yes, as long as the result is readable. Compression only reduces image detail; it does not change the content. Keep your original, full-quality file in case an office asks for a clearer copy later.
Privacy
Compress PDF runs inside your browser, so your certificates and ID documents are never uploaded to our server. You can even use it on a slow connection once the page has loaded.