PDF Basics

How to Reduce PDF File Size

This problem nearly always arrives with a hard number attached: under 2 MB, under 500 KB, under 100 KB. Working backwards from the limit is the fastest way to hit it.

4 min readUpdated 14 September 2026Dockeazy editorial

The short answer

Compression is the first thing to try and often enough on its own. If the file still will not fit, remove pages you do not need, or rescan at a lower resolution — that usually achieves more than compressing twice.

Compress PDF

Shrink file size while keeping the best quality.

Open Compress PDF

Step by step

1Compress the file firstFor anything containing scans or photographs this alone often solves it.
2Check how close you gotIf you are within a small margin of the limit, a stronger compression level will usually close the gap.
3Remove pages you do not needPortals rarely need the whole document. Sending four relevant pages instead of twelve is a large saving before compression even runs.
4Rescan if the source is a scanA 200–300 DPI greyscale scan is a fraction of the size of a 600 DPI colour one, and remains perfectly legible.

Work out where the size actually is

Divide the file size by the page count. A text document usually lands somewhere around 50–200 KB per page; a scan can be several megabytes per page.

That single number tells you which problem you have. High per-page size means images are the issue and compression will help substantially. Low per-page size across many pages means the page count is the issue, and removing pages is the only real lever.

Hitting very small limits

Caps around 100 KB are common on Indian government and university portals, and they are genuinely tight for a scanned document.

Greyscale instead of colour is the biggest single win — colour information often accounts for most of the size with no benefit for a black-ink form. Scanning at 200 DPI rather than 600 is the next.

For a one-page document, converting to an image and back can occasionally squeeze under where nothing else will. You lose selectable text, so only do this when the limit leaves no alternative.

What not to bother with

Renaming the file, zipping a PDF, or changing the extension do nothing. PDFs are already compressed internally, so a ZIP typically saves a percent or two.

Compressing the same file repeatedly has sharply diminishing returns and degrades images each time. One pass at the right level beats three at a light one.

Frequently asked questions

What is a normal PDF file size?

Text documents are commonly 50–200 KB per page. Scanned pages can be several megabytes each, which is why scans dominate file size.

Does zipping a PDF make it smaller?

Barely. PDFs are already compressed internally, so a ZIP usually saves only a percent or two.

Why is my scanned PDF so large?

Each page is a photograph rather than text, especially at high DPI in colour.

Will compressing make it unreadable?

No. Text stays sharp because it is not stored as pixels. Very strong settings soften images, so check any small print or stamps.