Job portals, exam registrations and government forms sometimes limit uploads to 100KB or 200KB. A typical scanned page is several megabytes, so the gap is big. It can be closed, but not always with a single click, and it helps to be realistic about what is possible.

First, how much room do you have?

Check the current size and the page count. Roughly speaking, you have a budget of 100KB divided by the number of pages.

• A one-page text document from Word or Google Docs is usually already tiny and compresses easily.
• A one-page scan can often reach 100KB with strong compression and a lower-quality scan.
• A 10-page scan is a different problem: that leaves about 10KB per page, which is very hard without making the text hard to read.

Step 1: compress at the highest level

Open Compress PDF, upload the file and choose High. Download it and check the size. For many single-page documents this is enough. Always open the result and confirm the text is still readable at normal zoom.

Step 2: shrink what you feed in

If it is still too big, the image data is the problem, so fix it at the source:

• Rescan at 150 DPI or lower instead of 300 or 600.
• Choose black and white for text documents; colour and greyscale cost far more space.
• Crop out borders and desk with Crop PDF.
• Try Grayscale PDF if you can't rescan.

Step 3: reduce the page count

If the portal only needs certain pages, Extract Pages or Delete Pages removes the rest. Fewer pages means more space for each.

Step 4: split if the portal allows several files

Some portals accept multiple uploads. If so, cut the document into parts with Split PDF and compress each part. Check the portal instructions first so you don't break its rules.

If nothing gets you there

Sometimes a file simply cannot be made that small without hurting readability. Options in that case: ask the portal's help desk whether they accept a larger file or an alternative format, or recreate the document as a text PDF (type it up, then export from your word processor), which is dramatically smaller than a scan.

For less demanding limits, our guide to compressing a PDF for email covers the usual 10 to 25 MB range.

Frequently Asked Questions

Will a 100KB PDF be readable?

For text documents at a sensible scan resolution, yes. Fine print, photos and stamps may look softer, so check before uploading.

Why won't my 20-page scan get under 100KB?

There isn't enough space per page. Reduce the page count, split the file or ask whether a larger limit is acceptable.

Is it better to compress or rescan?

Rescanning at lower resolution in black and white often gives the biggest saving.

Should I compress before or after merging?

After. Merge first, then compress the final file once.