PDF File Size Optimization

Compress PDF Online

Reduce PDF file sizes efficiently for easy emailing, sharing, and fast web uploads. 100% in your browser.

or drag and drop your PDF here

Local In-Browser Processing
.pdf • Private In-Browser Processing • Your file never leaves your device

Compression Level

Choose the ideal trade-off between file size reduction and image clarity

Awaiting PDF

Please select or drop a PDF file above to enable compression

Why Compress Your PDF?

• Bypass Email Limits: Stay comfortably below strict 20MB or 25MB attachment limits enforced by major mail clients.

• Fast Web Downloads: Ensure visitors on mobile networks download your brochures or forms instantly.

• Portal Upload Compliance: Submit job applications, tax records, and coursework without hitting blocks.

• Preserve Typography: Embedded vector fonts and essential layout details remain sharp and fully readable.

Compress PDF Online for Free

Our free online PDF compressor reduces PDF file sizes so you can easily send attachments via email, satisfy strict online portal upload quotas, and speed up document loading times on the web.

All document processing happens entirely inside your web browser using client-side WebAssembly and JavaScript engines. Because your PDF is processed locally on your device, your private documents are never transmitted to or stored on remote cloud servers.

The tool offers three dedicated compression levels (Less, Recommended, and Extreme) designed to preserve readable text, crisp vector diagrams, and supported document structures such as bookmarks, links, and forms. The exact file-size reduction achieved depends on the underlying structure and media content of your source PDF.

File Size vs. Page Dimensions: Compressing a PDF shrinks data volume without altering physical paper measurements. If you need to change paper dimensions (such as converting between A4 and Letter) rather than reducing byte size, you can resize your PDF to standard or custom page sizes.

How PDF Compression Works

PDF files often contain redundant data, uncompressed content streams, and high-resolution images that add unnecessary megabytes. Our client-side optimization engine intelligently targets multiple layers of the PDF file structure:

1Raster Image Optimization

Re-encodes and downsamples embedded bitmap images (such as photo scans and graphics) when applicable to eliminate unnecessary pixel data while preserving visual clarity.

2Eligible Content Streams

Applies lossless Flate compression to page drawing commands, layout operators, and font metrics to strip raw, uncompressed byte overhead.

3Structural Object-Stream Overhead

Compacts PDF cross-reference tables and consolidates indirect object references to minimize structural file metadata without breaking document integrity.

4Duplicate Resource Consolidation

Streamlines redundant embedded font subsets and shared color spaces across multiple pages where currently supported by the format.

Choose the Right Compression Level

Different use cases require different trade-offs between file size and visual fidelity. Select the preset that best fits your document:

Less Compression

Highest Quality

Prioritizes highest image quality and visual fidelity with lighter compression. Ideal for graphic design portfolios, photography books, and print proofs.

Popular
Recommended

Balanced

Delivers balanced file size reduction while preserving crisp text, charts, and clean images. Optimal for daily office files, invoices, school projects, and email attachments.

Extreme Compression

Smallest File Size

Applies the strongest compression to achieve the smallest possible file footprint, with greater potential visual quality trade-offs for embedded images. Best for strict upload limits.

When Will a PDF Compress the Most?

Because PDF compression works by eliminating inefficiency and downsampling heavy media, the percentage reduction varies significantly based on how the original PDF was created:

  • High Reduction Potential: Documents containing large uncompressed raster images, high-DPI scans, photos from digital cameras or smartphones, uncompressed content streams, and redundant embedded resources have significant room for file-size reduction.
  • Moderate to Low Reduction Potential: Documents that consist almost entirely of plain text, standard vector fonts, minimal line art, or files that were already aggressively compressed by specialized desktop publishing software have little redundant overhead and may shrink only slightly.

How to Compress a PDF

  1. 1

    Choose the PDF

    Drag and drop your PDF into the upload area above or click to select a document from your computer or mobile device.

  2. 2

    Select Compression Level

    Select Recommended for general use, Less to retain maximum image fidelity, or Extreme for minimum file size.

  3. 3

    Start Compression

    Click the "Compress PDF" button to execute the optimization pipeline locally in your browser.

  4. 4

    Download the Optimized PDF

    Compare the original versus final file size and percentage reduction, then download your optimized PDF immediately.

Frequently Asked Questions

How do I reduce PDF file size?

Upload your PDF document to the tool above, pick your preferred compression profile (such as Recommended), click Compress PDF, and download the reduced file upon completion.

Can I compress a PDF without changing the page size?

Yes. PDF compression optimizes internal stream encoding and embedded image resolution while leaving physical page dimensions (like A4 or Letter) unchanged. If you want to change physical page dimensions, use our Resize PDF tool.

Why did my PDF only shrink a little?

If your PDF was already optimized during export, contains purely vector text without heavy raster images, or was previously compressed, there is very little redundant data available to remove.

Does compression affect text quality?

No. Text glyphs and vector geometry are retained as scalable paths and are compressed with lossless algorithms. Only raster bitmap images are subject to downsampling depending on the compression level chosen.

Is the PDF uploaded to a server?

No. All compression algorithms execute strictly inside your browser environment using local computing resources. Your files are never uploaded to, transmitted over, or saved on any remote servers.

Need to change page dimensions instead?

Compressing reduces file size. If you need to change paper sizes to A4, Letter, or custom dimensions, use our page resizer.

Resize PDF