How to Compress a PDF Without Losing Quality
PDFs balloon in size for one main reason: embedded images. A report full of high-resolution screenshots or a scanned contract can hit tens of megabytes. The good news is you can shrink most PDFs dramatically while keeping the text perfectly crisp — because text and images compress very differently.
Why PDF text never gets blurry
Text in a well-made PDF is stored as vector data (font outlines and positions), not pixels. Vectors are tiny and scale perfectly, so compressing a PDF barely touches them — your text stays razor-sharp and fully selectable at any size. What actually takes up space, and what compression targets, is the raster imagery.
What PDF compression actually does
- Downsamples embedded images to a sensible resolution — 150 DPI is plenty for on-screen reading, 300 DPI for print. A 600 DPI scan downsampled to 150 DPI shrinks roughly 16× for that image.
- Recompresses image streams with efficient codecs.
- Subsets fonts so only the characters you use are embedded.
- Strips redundant metadata and unused objects.
Choosing the right level
| Use case | Target |
|---|---|
| Email / web viewing | ~150 DPI (“screen/ebook”) |
| General sharing | ~150–200 DPI |
| Printing | 300 DPI (“print/prepress”) |
Going below ~150 DPI is where images start to look soft — that's the line to watch if quality matters.
Extra tips
- Grayscale a document with no meaningful color to shrink it further.
- Start from the highest-quality source and compress once, rather than re-compressing an already-shrunk PDF.
- For pure-text PDFs, there's often little to compress — the file is already small because there are no heavy images.
FreeCompressor's PDF tool
Our browser-first PDF Compressor is in active development — it will downsample images, recompress streams and subset fonts while keeping text selectable. Add your email on the tool page to be notified the moment it launches. If you need to shrink images inside a document today, the image compressor is already live.