Compress PDF Online — Compare File Size
Rebuild a PDF with browser-side save settings and compare the original size with the output size. Some already-optimized PDFs may not get smaller, so use the measured result before downloading.
Drop your PDF here or click to browse
How to Compress a PDF
- Upload your PDF — Drop a PDF file onto the upload area or click to select one from your device.
- Choose compression level — Select Low, Medium, or High to run the browser-side rebuild with the available save settings.
- Compare the result — Click Compress PDF, review the original and output sizes, then download only if the result works for your file.
Features
- 3 browser-side compression levels
- Shows before/after file size
- Visual savings percentage bar
- Reports when the rebuilt PDF is not smaller
- Powered by pdf-lib
- Free, no signup required
Compress PDF online: measured before and after sizes
Use Compress PDF to rebuild a PDF in your browser tab and compare the original size with the saved result. The page shows measured before/after sizes so you can decide whether the file actually became smaller.
Example workflow
Upload a proposal PDF before emailing it, run medium compression, and compare the displayed sizes. If the page reports no reduction, the source file is probably already optimized for this browser-based method.
Limits to check
- Reduction: Compression is not guaranteed; already-optimized PDFs may not shrink.
- Quality: Review the downloaded PDF before sharing it, especially when the file has images or complex page content.
- Memory: Very large PDFs can be limited by browser memory.
For the next step, try Merge PDF Files Online, Split PDF, Edit PDF, PDF to JPG Converter.
Frequently Asked Questions
How much can PDF compression reduce file size?
Results depend on the PDF. This browser-based tool rebuilds the file and shows measured original and output sizes, but it does not guarantee a smaller result.
Will compression affect PDF quality?
The current browser method rebuilds the PDF with save options. Review the downloaded file before sharing it, especially when the PDF contains images or complex page content.
What if the compressed PDF is larger than the original?
This can happen with already-optimized PDFs. The page reports no reduction when the rebuilt file is not smaller.
What is the maximum file size supported?
There is no explicit file-size limit in the page script. Very large PDFs may be slow or fail if the browser does not have enough memory.
