Compress PDF

Large PDF files are a constant nuisance: they bounce back from email size limits, fill up cloud storage, and take ages to upload to portals. Compressing a PDF reduces its file size so it travels and stores more easily, without you having to recreate the document.

ColaPDF applies lossless optimisation — it removes unused objects, duplicate resources and redundant cross-reference data while leaving your text, fonts and vector graphics untouched. The reduction you see depends heavily on how the PDF was originally produced, but the process never degrades readable content.

How it works

1. Upload the PDF you want to compress
2. ColaPDF removes unused objects, redundant data and optimises cross-references
3. Click Compress PDF
4. Download the compressed file and see how much space was saved

Tips

• Image-heavy PDFs usually shrink the most; documents that are already optimised may barely change.
• If a file does not get smaller, it is most likely already well-compressed — that is a good sign, not a failure.
• Compress as the final step, after merging or editing, so you optimise the finished document.

Frequently asked questions

How much will it compress my PDF?

Results vary. Text-heavy PDFs compress less than image-heavy ones. PDFs already optimised may see little reduction.

Does compression affect quality?

This tool uses lossless compression — text, fonts and vector images are unaffected.

Are my files uploaded to a server?

No. Compression runs entirely in your browser.

My file didn't get smaller — why?

The PDF may already be optimised. In that case, the tool will tell you no further reduction is possible.