How to reduce a pdf's file size using lossless compression
- Step 1Upload the oversized PDF — Drop the document into the lossless compressor.
- Step 2Compress losslessly — Optimise internal streams and remove redundant objects.
- Step 3Check the file size reduction — The tool reports the original and compressed size.
- Step 4Download the optimised PDF — Save the losslessly compressed file.
Frequently asked questions
What if lossless compression is not enough to meet a file size limit?+
If you must hit a specific file size limit (e.g., 5MB for an email attachment), use lossy compression instead, which compresses images to reduce size further.
Does lossless compression affect metadata?+
Metadata is preserved. If you want to remove metadata for privacy, use the PDF Metadata Scrubber tool after compression.
Is lossless compression available for scanned PDFs?+
Yes — scanned PDFs with image pages benefit from lossless image compression (e.g., JBIG2 for black-and-white scans).
Privacy first
All PDF processing runs locally in your browser using PDF-lib and pdf.js. No file is ever uploaded — only metadata counters are saved for signed-in dashboard stats.