Compress PDF Free Online

PDFs can balloon in size for a few common reasons. Embedded images are the biggest culprit — a single high-resolution photo can add several megabytes. Fonts are another factor: when a PDF embeds full font families instead of just the characters it uses, the file grows quickly.

Editing also plays a role. Every time you revise a PDF in certain editors, leftover objects from previous versions pile up inside the file. These redundant objects don't affect what you see on screen, but they quietly inflate the file size. Compression cleans all of that up.

It depends on what's inside. Scanned documents with large raster images typically shrink by 20–50%. PDFs created by merging multiple files often contain duplicate resources and can drop 30–60% after compression. On the other hand, a PDF that was already exported with optimization in mind may only shrink a few percent — there's simply less waste to remove.

The before-and-after display on this page shows you exactly what you saved, so there are no surprises.

If you're scanning documents, use 150–200 DPI instead of 300+ — it's plenty for text and keeps file sizes manageable. When editing in apps like Word or InDesign, use "Save As" instead of "Save" to avoid accumulating hidden revision data.

If you merge several PDFs into one, run compression afterward. Merging often duplicates shared resources like fonts across the combined file, and a quick compression pass consolidates them back down.