PDF Compressor — Reduce PDF File Size Free Online

What This Tool Does

The PDF Compressor reduces the file size of PDF documents by optimizing embedded images, removing redundant metadata, and applying more efficient compression to the document structure. The result is a smaller PDF that is identical in appearance and content to the original.

PDF compression is primarily effective when the document contains embedded images (photographs, scanned pages). Text-only PDFs are already very small and compress minimally.

How to Use the PDF Compressor

• Upload your PDF file
• Select a compression level: Screen (maximum compression), Ebook (balanced), Printer (high quality), or Prepress (professional quality)
• Click Compress
• Review the size reduction and download your compressed PDF

Compression Levels Explained

Why Are PDFs Large — and How Compression Helps

PDF file size is largely determined by embedded content. The three biggest contributors are:

• Embedded images — scanned pages, photographs, and logos stored at print resolution (300+ DPI) are the primary cause of large PDFs
• Embedded fonts — full font files embedded in the PDF can add several hundred KB each
• Metadata and structure — document properties, version history, and XML metadata add minor overhead

PDF compression works primarily by downsampling embedded images — reducing their resolution from print quality (300 DPI) to screen quality (72–150 DPI). For a document that will only be read on screen, 72–150 DPI is visually indistinguishable from 300 DPI. This image downsampling accounts for most of the file size reduction.

When to Compress vs When Not To

Compress when:

• Sending PDFs by email (most services have 10–25MB limits)
• Uploading to web forms with file size restrictions
• Storing large numbers of PDFs in cloud storage
• Sharing documents for screen viewing only

Do not compress when:

• Sending files to a commercial printer (use Prepress settings at minimum)
• The PDF contains fine details that must be preserved at high resolution
• Legal or archival documents requiring exact preservation

Privacy & Security

PDF compression runs in your browser. Your documents — legal contracts, financial statements, medical records, or any sensitive material — are never transmitted to any server. This is fundamentally more private than cloud-based tools like Smallpdf, ILovePDF, or Adobe Compress online, which all upload your files to their servers.

Common Problems & Fixes

• PDF doesn't compress much — the document may be text-only or already compressed. Text PDFs are typically already small (under 100KB per page).
• Images look blurry after compression — use a higher quality setting (Printer or Prepress). The Screen setting uses 72 DPI which is visibly low for detailed images.
• File is larger after "compression" — this can occur with very small PDFs where the compression overhead exceeds the savings. Already-optimized PDFs cannot be further reduced.
• Password-protected PDF won't compress — remove the password protection before compressing.

PDF Compression in Your Document Workflow

Compress PDFs as the final step before sharing — after converting — whether from Word to PDF, Excel to PDF, or PowerPoint to PDF and merging:

• Convert Word to PDF first, then compress the result
• Convert Excel to PDF and compress for email attachments
• Merge multiple PDFs then compress the combined file
• Split the PDF into smaller sections — individual sections are smaller to compress and share separately
• Compress images inside your PDF source documents before converting to reduce the PDF size further

Related Tools

• If the PDF contains tables you need, extract them to Excel rather than compressing the whole document. → extract data from the PDF instead of compressing
• Creating PDFs programmatically? An HTML-generated PDF is often smaller than a scanned or exported PDF. → generate a leaner PDF from HTML source