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Compress PDF Online Free

Reduce PDF file size without quality loss. Runs in your browser. Great for reducing PDF file sizes before emailing, uploading to portals, or storing in the cloud.

Files processed in your browser — never uploaded to our servers

Click or drag a PDF here

Single PDF file

What is Compress PDF Online Free?

PDF compression reduces file size while preserving content. PDFs vary enormously in size depending on how they were created: scanned PDFs are essentially bitmap images embedded in a PDF container and can be 10–50 MB per page, while text-native PDFs generated from a word processor are tiny — under 1 MB for 50 pages. There are two types of compression: lossy compression reduces image quality to achieve smaller file sizes, and lossless compression removes redundant metadata and unused internal objects without touching quality at all. For most email and web use cases, medium-quality compression is visually invisible on screen and can reduce file size by 60–80%, making the difference between a rejected upload and a successful submission.

How to use

  1. Upload your PDF by clicking the drop zone or dragging the file in.
  2. Click Compress PDF to reduce the file size using lossless structure optimisation.
  3. Review the size reduction percentage shown in the result panel.
  4. Click Download Compressed PDF to save the smaller file to your device.

Why it matters

Email attachments are commonly capped at 10–25 MB by mail servers, and many form upload fields impose a 5 MB or 10 MB limit. A scanned document at original quality can easily exceed these limits and result in a bounced email or a failed upload. Compressing before sending prevents rejected submissions and avoids the back-and-forth of asking recipients to use file-sharing services. For PDFs hosted on websites, smaller files also load faster in browser PDF viewers, improving the experience for readers on slower connections.

Pro tip

All processing happens entirely in your browser — no files are uploaded to any server. Your documents never leave your device. If your PDF contains text-only pages alongside scanned images, try compressing once and then evaluate whether the quality is acceptable. Most people cannot visually distinguish a compressed PDF image at 80% quality from the original when viewed at normal zoom on a screen.

Frequently Asked Questions

We re-encode the PDF structure using object stream compression. This reduces file size for many PDFs, especially those with redundant metadata or unoptimised object streams.
This tool compresses the PDF structure, not the embedded images. Image quality is preserved.
Some PDFs are already well-optimised. If images are the main size contributor, further reduction would require lossy image recompression.
No. Compression runs entirely in your browser. Your file never leaves your device.
Results vary depending on the PDF. Files with lots of redundant metadata or unoptimised object streams can shrink by 20–50%. Already-optimised PDFs may see little or no reduction.
No. This tool compresses the PDF document structure, not the text or fonts embedded inside it. All text remains fully readable and searchable after compression.
The most common causes are high-resolution embedded images, unoptimised object streams, embedded fonts, and redundant metadata. Image-heavy PDFs tend to have the most room for size reduction.
There is no strict limit, but very large files (100MB+) may be slow to process depending on your browser and device memory. We recommend files under 50MB for best performance.
Currently the tool compresses one file at a time. Compress the first file, download it, then upload the next one.
Zipping creates a compressed archive container but does not reduce the internal size of the PDF itself. PDF compression reduces the size of the file's internal structure, so the resulting PDF is smaller even without a ZIP wrapper — making it easier to email directly.