How to compress a PDF without losing quality
Most compressors trade size for visible quality loss. Here is how to shrink a PDF while keeping text crisp, vector graphics sharp, and only image quality even slightly affected — all in your browser.
Open the Compress PDF tool →The phrase “compress without losing quality” sounds like a contradiction, but it is mostly an honest one. Text and vector graphics in a PDF can be re-compressed losslessly. It is only the embedded raster images that involve a size-versus-quality trade. The trick is being conservative on images — and most PDFs have images stored at way higher resolution than they are ever displayed at.
What stays the same, what changes
Compressing a PDF in this tool touches three kinds of content differently:
| Content type | What happens | Quality impact |
|---|---|---|
| Text | Re-encoded losslessly | None |
| Vector graphics (logos, charts) | Re-encoded losslessly | None |
| Raster images (photos, scans) | Downsampled + re-JPEGed | Depends on preset |
So when you compress a contract that is “mostly text with a logo on each page”, the entire savings come from the logo treatment and the bytes saved by smarter encoding — and you usually lose nothing visible.
Pick the preset that matches your tolerance
- Low (recommended for “no visible quality loss”) — keeps images near their original DPI, uses high JPEG quality. Savings are smaller but the file is indistinguishable from the original on screen and in print.
- Recommended (the default sweet spot) — downsamples images to ~150 DPI. Text and vectors are untouched. Most users cannot tell the result from the original on screen. Print quality is acceptable for office printing, not for press.
- High — drops image DPI to ~72. Visible compression artifacts on images become possible. Good for screen-only viewing where the file size is the constraint (email attachment limits, web form caps).
The “without losing quality” promise really means: pick Low. If “no visible quality loss on a monitor” is enough, Recommended is almost always indistinguishable.
How to spot-check the result
After compression, open the new PDF and look at:
- Any embedded photo or scan. Zoom in — that is where artifacts would show first.
- Logos and line art. These should be pixel-identical (vectors are lossless).
- Text on dense pages. Confirm it is still selectable. If text is no longer selectable, the file was probably an OCR’d scan and the OCR layer dropped; re-OCR if you need searchability.
Why our compress is different
Many online PDF compressors strip metadata, remove embedded fonts, or even rasterize text-heavy pages — making the result smaller but harder to search and visually worse. We use Ghostscript with conservative defaults: text and vectors are never rasterized, fonts are preserved unless they are duplicated, and the bulk of the savings come from image handling.
Privacy
Compressing happens in your browser via Ghostscript compiled to WebAssembly. Your PDF is processed locally and never uploaded — Network tab will confirm zero outbound file requests during the operation.
Step by step
- Open the Compress PDF tool.
- Drop your PDF on the upload area.
- Pick "Low" if archival quality matters, or "Recommended" if screen viewing is fine.
- Click "Compress PDF" and compare the before-and-after sizes.
- Open the result and spot-check the pages you care about most.
FAQs
- What does "without losing quality" actually mean for a PDF?
- Text and vector graphics (line art, logos, charts) can usually be re-compressed losslessly — they look identical before and after. Embedded raster images are the only part where you trade size for fidelity. So "no quality loss" really means "no visible quality loss on the parts you care about", typically by being conservative with image downsampling.
- Which preset preserves the most quality?
- “Low” — it keeps image DPI close to the original (around 300 DPI) and uses higher JPEG quality. Savings are smaller (typically 10–40% on image-heavy files, nearly none on text-only files), but the result is virtually indistinguishable from the original on screen and on print.
- Why does "Recommended" lose so little visible quality despite shrinking files by 50%+?
- Most PDFs have embedded images stored at much higher resolution than they are ever displayed at — for example, a phone photo scanned in at 600 DPI and displayed at 100 DPI. Downsampling to 150 DPI removes pixels you would never see anyway. Text and vectors are untouched.
- Is the file uploaded for this?
- No. The Ghostscript engine that does the compression runs inside your browser as a WebAssembly module. Your PDF is shrunk locally on your device — the Network tab will show no file uploads.
Related guides
- Make a PDF under 2 MB 2 MB is the most common file-size cap on web forms — visa applications, school portals, support uploads. Here is how to hit it in your browser, without uploading the file you are shrinking.
- Make a PDF under 10 MB 10 MB is the everyday upload cap — most email providers, Slack, many ticketing systems. Here is how to comfortably clear it in your browser, without uploading the file you are shrinking.
- Compress a scanned PDF Scanned PDFs are usually mostly image — and image PDFs shrink dramatically. Here's how to compress a scanned PDF in your browser without sacrificing legibility.