How to Compress a PDF Without Losing Quality

A PDF that's too large to email is a surprisingly common problem, and it's almost always caused by images — scanned pages, embedded photos, or a document exported at print resolution when it only ever needed to be viewed on a screen.

Why PDFs get big in the first place

Text itself takes up very little space in a PDF. The size usually comes from embedded images: a scanned document is really just a series of high-resolution photos stitched together, and each one can be several megabytes on its own.

How to compress a PDF

1. Open the Compress PDF tool.
2. Upload the file you want to shrink.
3. Let it process — compression re-encodes embedded images at a lower resolution.
4. Download the smaller file and check it still looks right.

What actually happens during compression

Compression reduces the resolution and re-encodes the images inside the PDF, a form of lossy compression. Text stays sharp, because text in a PDF is stored as vector data or font references, not pixels — it isn't touched by image compression at all. What you're trading is image sharpness for file size, which is usually a good trade for a document that's being emailed or read on-screen rather than printed at high quality.

If quality matters more than size

For documents you plan to print — especially anything with photos or fine print — keep a copy of the original alongside the compressed version. Compression is meant for sharing and storage, not as a replacement for your source file. And if you only need some of the pages, extract just those pages instead — a shorter document is smaller without losing any quality.