How to compress a scanned PDF for an upload limit

A scan can weigh several megabytes even when it contains just a few pages. Each scanned page is already an image. Reducing that image’s detail can shrink the file considerably, but small text, stamps, and fine lines are the first things to suffer.

Check the upload rule first

Read the limit in the upload form. Check whether the limit applies to each file or to all attachments combined. If the form allows multiple PDFs, splitting the document may preserve more detail than applying strong compression to everything.

If you spot a blank scanner page or a duplicate, remove it with Remove PDF Pages before compressing. Keep the source file as a separate copy.

Choose a compression level

1. Open Compress PDF and choose the original scan.
2. Start with Medium and select Compress PDF. The result message shows the original and compressed sizes when the tool saves a smaller copy.
3. Open the new PDF at normal zoom and then zoom in on the smallest text. Check every page that contains a stamp, a signature, or a thin line.
4. If the result is still too large, try Strong on the original. If the text is hard to read, try Light or use Split PDF if separate files are accepted.

For a 2 MB limit, a readable 1.8 MB result is usually the better choice over a blurrier 900 KB copy. Once you meet the limit, check quality before chasing a smaller number.

Know when to keep the original

This compressor renders each page as an image in a new PDF. That is useful for scans but removes selectable text, interactive links, and fillable form fields. Keep the original if the recipient needs those features. The tool may also decline to save a new copy if an already optimized PDF barely shrinks. In that case, leave it alone or rescan at more appropriate settings.

Work out what made the scan large

Compare the file with another scan of the same document if you have one. A scan with wide, shaded margins or a photograph on every page may react differently from a clean black-and-white letter. Colour can matter for a stamp, annotated chart, or coloured mark, so keep it when the recipient relies on it. If the document is still available digitally, exporting the original to PDF can produce cleaner text and a smaller file than scanning a printout.

Avoid repeatedly compressing the last result. Each pass starts from the detail that survived the previous one. If Medium failed to meet the cap, go back to the original or the cleaned copy and try Strong once. That gives you an honest comparison between the two settings.

Check the result against the actual submission

Make a quick review list of the pages with the smallest text or the greatest consequences if detail is lost. On a five-page application, that might be the serial number on page two, a signature on page four, and the full date on page five. Verify that the compressed PDF still has all five pages in the correct order. Then check the file size on the device you will use to submit it.

If the limit is unusually tight, see what to try for a 100 KB PDF. If the original has selectable text or links you need to keep, start with the PDF compressor comparison before committing to a method.