Compress PDF Online
Reduce PDF file size by up to 90%. Choose compression level for the best balance of size and quality. Free, no signup.
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Supports M4A, WAV, FLAC, OGG, AAC, WMA, AIFF, OPUS • Max 100 MB
Encrypted upload via HTTPS. Files auto-deleted from our servers within 2 hours.
How to Compress a PDF
1
Upload
Drag and drop your PDF into the tool above, or click to browse. Files up to 100 MB.
2
Choose Level
Select compression: Maximum for smallest file, Balanced for best trade-off, or High Quality for print-ready output.
3
Download
Click Compress & Download and get your smaller PDF. The result shows exactly how many bytes you saved.
Compression Levels Explained
| Level | Image DPI | Typical Reduction | Best For |
|---|---|---|---|
| Maximum | 72 DPI | 70–90% | Email attachments, web uploads, file size limits. Text stays sharp, images are screen-resolution. |
| Balanced | 150 DPI | 40–70% | General use, sharing, archiving. Good image quality with significant size savings. Recommended default. |
| High Quality | 300 DPI | 20–40% | Printing, professional documents. Images remain sharp at print resolution. |
| Max Quality | Original | 5–20% | Prepress, archival. No image downsampling — only stream compression and font optimization. |
What Gets Compressed in a PDF?
A PDF file contains multiple types of data. Each responds differently to compression:
- Embedded images — the biggest contributor to file size. Our compressor downsamples images to the target DPI and re-encodes them with JPEG compression. A 20 MP photo embedded at 300 DPI can shrink from 15 MB to under 1 MB at the Maximum setting.
- Fonts — PDFs often embed entire font files (300+ KB each). Compression subsets fonts to include only the characters actually used in the document.
- Content streams — the text, vector graphics, and page layout instructions. These are recompressed with Flate (zlib) compression for maximum efficiency.
- Metadata — creation date, author, software info. Minimal impact on file size but gets cleaned up during reprocessing.
Note: Text-only PDFs (no images) are already very small and may not compress significantly. The biggest savings come from PDFs with embedded photos, scanned pages, or high-resolution graphics.
Common Use Cases
| Scenario | Recommended Level | Why |
|---|---|---|
| Email attachment (under 10 MB) | Maximum or Balanced | Most email providers limit attachments to 10–25 MB. Maximum compression gets large PDFs under the limit. |
| Government portal upload | Balanced | Many portals require PDFs under 2–5 MB. Balanced preserves readability while meeting size requirements. |
| Web download / sharing | Balanced | Faster downloads, less storage. 150 DPI is plenty for screen viewing. |
| Print-ready document | High Quality | 300 DPI preserves image sharpness for laser/inkjet printing while still reducing font and stream overhead. |
| Archival / prepress | Max Quality | No image downsampling. Only optimizes internal structure, fonts, and stream compression. |
Frequently Asked Questions
It depends on the PDF content. PDFs with high-resolution images (scanned documents, photo books, presentations with embedded photos) can be reduced by 70–90% using Maximum compression. Text-heavy PDFs with few images typically compress by 10–30%. Scanned documents often see the biggest savings because they are essentially large images wrapped in a PDF container.
Text is always preserved at full quality — compression only affects embedded images. At the “Balanced” setting (150 DPI), images look great on screens and are readable when printed. “High Quality” (300 DPI) is indistinguishable from the original for most documents. Only “Maximum” (72 DPI) noticeably reduces image sharpness, but text remains perfectly crisp.
Yes, completely free with no limits. No signup, no watermarks, no file count restrictions. Upload as many PDFs as you need. Your files are encrypted via HTTPS and automatically deleted from our servers within 2 hours.
No, password-protected PDFs cannot be processed. You’ll need to remove the password first using your PDF reader (Adobe Acrobat, Preview on Mac, or a PDF password removal tool), then upload the unprotected file.
Yes, and scanned PDFs benefit the most from compression. A scanned document is essentially a large image (often 200–600 DPI) saved as PDF. Compressing it to 150 DPI (Balanced) can reduce a 20 MB scan to 2–3 MB while keeping text clearly readable. For archival scans where you need every detail, use High Quality (300 DPI).