PDF Compressor

Honest expectations: how much smaller will your PDF get?

Most PDF compression tools oversell their results. Here is what you can realistically expect from each mode.

Lossless mode rewrites the PDF's cross-reference tables using object streams, which pack references more compactly, and removes metadata fields like title, author, subject, and producer. For a PDF freshly exported from a modern tool — Word, Google Docs, InDesign — these savings are typically modest: somewhere between 0% and 15%. Some PDFs come out exactly the same size. That is not a bug; it means the file was already well-structured.

Strong (rasterize) mode renders every page to a JPEG and builds a new PDF from those images. For scanned documents, photographs, and slide decks full of embedded images, this can reduce the file by 50–80%. The trade-off is significant: all text becomes part of the image. You lose text selection, copy-paste, search, and screen-reader accessibility. Use this mode only when file size matters more than document functionality.

How to use this tool

1. Upload your PDF using the drop zone or file picker.
2. Select Lossless (safe, preserves text) or Strong (maximum reduction, text becomes image).
3. In Strong mode, choose JPEG quality (40–90%) and resolution scale (1×–2.5×).
4. Click Compress PDF and wait for the result.
5. Review the before and after sizes. If compression made the file larger, the tool says so and offers the original for download instead.

Privacy and security

Your file never leaves your device. All processing runs in JavaScript inside your browser using pdf-lib for the lossless path and PDF.js for rasterisation. There are no server calls, no cloud uploads, and no temporary files stored anywhere outside your browser's memory. Once you close or refresh the tab, the file is gone. This makes the tool suitable for confidential documents: contracts, payslips, passports, medical records.

Related PDF tools

• Need to combine several PDFs before compressing? Merge PDFs combines multiple files into one document.
• Only need a subset of pages? Remove PDF pages to trim the document before compressing.

Frequently asked questions

How much smaller will my PDF get?

It depends on the PDF. Lossless mode strips metadata and re-encodes the file structure — you might see a reduction of 1–15%, or sometimes no change at all if the file is already well-optimised. Strong (rasterize) mode can cut image-heavy or scanned PDFs by 50–80%, but at the cost of making text non-selectable.

Why did Lossless mode barely change the size?

That's normal and expected. Lossless optimisation removes metadata (title, author, subject, keywords) and rewrites cross-reference tables more compactly. Modern PDF exporters already produce lean files, so there may be very little redundancy to remove. If your PDF contains large embedded images or fonts, only Strong mode will substantially reduce the size.

What does Strong mode do to text?

Strong mode renders every page to a JPEG image and rebuilds the PDF from those images. As a result, all text becomes part of the raster image — it is no longer selectable, searchable, or copy-pasteable. If you need to retain selectable text, use Lossless mode or skip compression entirely.

Is my PDF uploaded to a server?

No. Everything happens inside your browser using JavaScript. Your file is read from disk into memory, processed locally, and written back out — it never leaves your device and is never sent over the network. This makes the tool safe for confidential documents like contracts, medical records, or financial statements.

What if the compressed file is larger than the original?

The tool detects this automatically. If the output after processing is not smaller than the original, it tells you honestly and offers the original file for download rather than a larger version. You won't accidentally end up with a bigger PDF.