Compress a PDF to Reduce Its File Size
Shrink a PDF with one of two honest methods: a lossless rewrite that keeps everything intact, or strong compression that turns each page into a JPEG — ideal for bulky scans. You see the exact size before and after.
How to compress a PDF
- Choose the PDF you want to make smaller.
- Pick Lossless optimise to keep text and quality, or Strong to rasterise pages for maximum savings.
- For Strong mode, set the resolution and JPEG quality (and optionally grayscale).
- Select Compress PDF, compare the original and compressed sizes, and download the version you prefer.
Supported formats
- Input
- Output
- Maximum size
- 200 MB per file (limited by your device's memory)
Which method should I use?
Lossless optimisation removes unused objects left behind by earlier edits, packs objects into compressed object streams and can strip metadata and editor data. It never changes how pages look, but savings are typically small (0–20%) for files that were already well made. Strong compression redraws every page as a JPEG at the resolution you choose. It can cut a 40 MB scanned document to a few megabytes, but text becomes part of an image: it can no longer be selected, searched or read aloud, and links and form fields disappear. For text-heavy PDFs strong mode can even make the file bigger — the tool tells you when that happens. To pull the text out before rasterising, use PDF to Text; to shrink photos before building a PDF, try the Image Compressor.
Benefits
- Clear before/after sizes and percentage, with a warning (and the original offered) if the result is larger.
- Strong mode gives real control over resolution and JPEG quality instead of vague presets.
- Confidential documents are compressed without being uploaded to a compression service.
Limitations
- Lossless mode cannot recompress images already embedded in the PDF, so savings are often modest.
- Strong mode makes text unselectable and removes links, bookmarks, annotations and form fields.
- Strong mode renders pages on the main thread with PDF.js; very long documents take time and memory, and encrypted PDFs are not accepted.
Privacy and security
Both methods run locally: lossless optimisation uses pdf-lib in a Web Worker, and strong mode renders pages with PDF.js on a canvas in this tab before rebuilding the PDF in the worker. Nothing is uploaded.
Read our privacy policy for details about the site as a whole.
Frequently asked questions
Why did my PDF hardly get smaller?
Most of a PDF's size is usually images and fonts that are already compressed. Lossless optimisation can only remove waste around them. If the file is a scan, strong mode will make a much bigger difference.
What resolution should I pick for strong compression?
120 dpi is a good balance for reading on screen. Choose 150 dpi if the document will be printed and contains small text, and 72–96 dpi when the smallest possible file matters most.
Can the compressed PDF be searched?
After lossless optimisation, yes — nothing about the text changes. After strong compression, no: every page is an image, and this tool doesn't add an OCR text layer.