Compress PDF
Shrink a PDF with Screen, Ebook, Printer, or Prepress quality profiles and an optional grayscale option.
Drag and drop your PDF file here or click to browse
Supported: .pdf files onlyCompression Tips
Match the profile to the use case
Use Screen for web viewing, Ebook for a balanced trade-off, and Printer or Prepress when print detail matters more than size.
Expect image quality trade-offs
Stronger compression can soften photos and scanned pages. Review the downloaded PDF before sharing.
Try grayscale on color-heavy files
When color is not needed, enabling grayscale can reduce size further on photo or diagram pages.
Four quality profiles
Choose Screen, Ebook, Printer, or Prepress; each maps to a different Stirling optimization level and size target.
Optional grayscale
Send a grayscale flag with the compress request when color is not required.
Single PDF output
Download one compressed PDF file after processing completes.
What this tool does
Compress PDF reduces file size by re-optimizing the document with a chosen quality profile and an optional grayscale flag.
Use it when a PDF is too large for email, upload portals, or storage—and you can accept some quality trade-offs.
How to use
Upload one PDF
Select or drag a single .pdf file into the tool.
Choose quality and grayscale
Pick Screen, Ebook, Printer, or Prepress, and enable grayscale if you want color removed.
Compress and download
Run compression and download the resulting single PDF.
Supported inputs and output
Input: one .pdf file, a quality value (screen | ebook | printer | prepress), and a grayscale boolean. Output: one compressed PDF.
Approximate upload limit from server middleware is about 100 MB.
Quality profile mapping
Screen
Optimize level 5 with a ~1 MB size target—favoring smaller files for on-screen use.
Ebook
Optimize level 4 with a ~2 MB target—a common default balance.
Printer
Optimize level 3 with a ~5 MB target—retaining more detail for printing.
Prepress
Optimize level 2 with a ~10 MB target—keeping more quality for print production.
Processing and privacy
Your PDF is posted to /api/converter/pdf-compress and processed on Toolomix servers through Stirling-PDF compression.
Toolomix does not publish a verified universal retention clock for every conversion. See the Privacy Policy for how uploads and logs are handled.
Limitations
Known limits
- Single PDF upload only—no multi-file batch
- Quality loss is possible, especially for images and scans
- Size targets are goals, not hard guarantees of final file size
- No password / encrypted-PDF unlock field
- No OCR
- Uploads near or above ~100 MB may be rejected by middleware
Worked example
Example workflow: upload a multi-page PDF that is larger than you want to email, choose a balanced compression profile, and download the result. Compare the on-page before/after sizes—reduction depends on images and prior optimization, so a already-compressed scan may barely shrink.
If the file is still too large, split out only the pages you need with PDF Split, then compress that smaller PDF again.
Troubleshooting
If compression fails, confirm the file opens locally, remove encryption, try a less aggressive profile, and keep the upload under ~100 MB.
If the file barely shrinks, it may already be optimized or contain little compressible image data—try grayscale or accept a modest reduction.
PDF Compression FAQ
What do the quality profiles map to?
Screen uses optimize level 5 with a ~1 MB target, Ebook level 4 / ~2 MB, Printer level 3 / ~5 MB, and Prepress level 2 / ~10 MB. Actual size depends on the source PDF.
Will compression always shrink the file?
Often yes for image-heavy PDFs, but already-optimized or text-only files may shrink little. Quality loss is possible, especially on images.
What does the grayscale checkbox do?
When checked, the compress request sets grayscale to true so color content can be converted during compression.
Can I compress password-protected PDFs?
No. There is no password field. Remove encryption before uploading.
Does compression run OCR?
No. The tool recompresses PDF content; it does not recognize text from scanned images.
Where is my PDF processed?
The file is uploaded over HTTPS to /api/converter/pdf-compress and processed on Toolomix servers via Stirling-PDF compress, then returned as a single PDF.
Can I compress multiple PDFs in one go?
No. Upload and compress one PDF per request.
Try Other Free Tools
Compress a PDF now
Pick a quality profile and shrink your PDF for sharing or storage.
