Reduce PDF Size Online
Reduce PDF file size online for free — pick your target size and we handle the rest.
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How to compress PDF
- Upload your PDF (up to 50 MB).
- Choose a compression level (Low, Medium, High, or Maximum).
- Click 'Reduce PDF Size' — takes 5-30 seconds depending on size.
- Download the smaller PDF.
Quick fact about PDF
PDFs are often large because they embed full-resolution images and fonts. Reducing the size means optimizing those embedded resources — typically 40-80% smaller with no visible quality loss on screen.
Why compress PDF?
PDFs are often much larger than they need to be — a 10 MB PDF from a scanner or design export can often fit in 2 MB with no visible change. Large PDFs are hard to email, slow to upload, and expensive to store. Our compressor optimizes the embedded images (the biggest source of bloat) and metadata, typically achieving 40-80% size reduction.
Technical details
| Input format | |
| Output format | PDF 1.7 |
| Typical reduction | 40-80% at Medium |
| Image compression | Downsample + re-encode |
| Text/vector | Preserved losslessly |
| Metadata | Cleaned |
| Engine | Ghostscript |
| Max file size | 50 MB per file |
| File retention | Auto-deleted after compression |
How the conversion works
The compressor analyzes the PDF's internal structure, downsamples high-resolution embedded images to screen-appropriate DPI, re-encodes them with efficient compression (JPEG for photos, Flate for graphics), and removes redundant metadata. Text and vector content are preserved losslessly. Output is PDF 1.7.
When to compress PDF
- Emailing large PDFs (many clients cap attachments at 10-25 MB).
- Uploading PDFs to systems with size limits.
- Reducing cloud storage costs for a PDF archive.
- Preparing PDFs for web download.
- Meeting upload caps on job portals and forms.
- Making a PDF easier to share over mobile networks.
- Optimizing scanned documents (usually the largest PDFs).
Quality considerations
At Medium (120 DPI), most PDFs look identical to the original on screens — text is perfectly sharp (it's vector), and images are downsampled to screen-appropriate resolution. Higher compression levels reduce image quality visibly.
Limitations and caveats
- Text and vector content is preserved (lossless).
- Embedded images are downsampled — may affect print quality.
- Scanned PDFs (image-based) compress well but text remains raster.
- Encrypted PDFs must be unlocked first.
- Very small PDFs (under 100 KB) may not benefit.
- Some very old PDFs may not compress as efficiently.
Compatibility
- Output PDF opens in every browser, reader, and OS.
- Text stays searchable and selectable.
- Editable in Adobe Acrobat, PDF-XChange, Foxit.
- Printable at the downsample resolution.
- Accepted by every document management system.
Tips for best results
- Medium (120 DPI) is the sweet spot — 50-70% smaller with no visible loss.
- Scanned PDFs often compress dramatically — try High if size is critical.
- Text stays sharp at every level (vector content is lossless).
- Keep the original PDF if print quality matters.
- Test with a small file first for very large PDFs.
Compression levels explained
| Level | Size reduction | Best for |
|---|---|---|
| Low (150 DPI) | ~30-50% | Print or high-quality viewing |
| Medium (120 DPI, default) | ~50-70% | Email, general sharing |
| High (96 DPI) | ~70-85% | Web display, strict limits |
| Maximum (72 DPI) | ~80-90% | Severe size limits |
Common problems and fixes
- Text looks blurry after compression
- Text is vector — it should stay sharp. If it looks blurry, the PDF was likely scanned (image-based text). Use a lower compression level for scans.
- PDF is barely smaller
- The PDF may already be optimized, or it contains mostly text (little to compress). Try the 'Maximum' level.
- Images look pixelated
- The compression level downsamples images. Use a lower level (Low or Medium) for higher image quality.
Frequently asked questions
Explore related tools
Sources and references
Last reviewed: 2026-10-01