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How to compress and reduce a PDF's size

Published 2026-08-20 · Tutorial

A heavy PDF won't go through email, slows down a website and fills the recipient's mailbox. Here is how to understand where the weight comes from, then lower it effectively.

Why is a PDF so heavy?

A PDF is generally heavy because it contains high-resolution images, embedded fonts or scanned pages. A multi-page scan can therefore reach tens of megabytes while containing only text.

Reduce without losing the text

A tool like Bang PDF offers a standard compression that keeps the text selectable while shrinking the file 15 to 30 %. For a scan, maximum optimization turns each page into a compressed image: the gain is spectacular but the text is no longer selectable.

Which level should I choose?

In short: for a text or a contract, choose 'Normal'. For a scan, a photo, a presentation, choose 'Maximum'. Test both and compare the shown saving percentage.

Good practices

A PDF's weight mostly comes from its images. Before producing a PDF, export your images at the right size (150-200 dpi is enough for screen). For printing, aim at 300 dpi.