What makes a PDF large — and how compression helps
Almost all the weight in a big PDF comes from images: phone photos, scanned pages and high-resolution graphics that were embedded at full size. Text and vector drawings take up very little room. This tool re-encodes those images at a sensible resolution and quality, removes leftover objects that are no longer used, and packs the file structure more tightly.
You choose how far to go. Light and Recommended keep every word selectable and searchable. Strong redraws each page as an optimised image, which gives the smallest possible file — ideal for scanned documents — at the cost of selectable text. The before and after sizes you see are the real sizes of the file you download.
How to compress a PDF
- 1
Choose your PDF
Select the file or drag it onto the page.
- 2
Pick a level
Recommended suits most documents. Use Strong for scans you only need to read or print.
- 3
Compress
Images are optimised one by one; a progress bar shows how far along it is.
- 4
Compare and download
Check the before and after sizes and the percentage saved, then download.
Key features
Real compression
Embedded photos are resized and re-encoded — the saving shown is the actual file size.
Keeps text selectable
Light and Recommended levels leave text, links and vector graphics untouched.
Strong mode for scans
Turns scanned pages into compact images, often shrinking them by 80–95%.
Honest results
If a file is already optimised, you're told so instead of getting a bigger file.
No upload
Compression runs locally, so confidential documents stay on your device.
Common uses
- Email attachments: Get under the 20–25 MB limit of Gmail and Outlook.
- Government and job portals: Many forms reject files over 1–2 MB; strong compression usually gets scans under it.
- Storage: Shrink archives of scanned paperwork before backing them up.
Which compression level should I use?
| Level | What it does | Best for |
|---|---|---|
| Light | Re-encodes photos at high quality, max ~2600 px | Brochures and reports you'll print |
| Recommended | Photos at ~1800 px, balanced quality | Email attachments and uploads |
| Strong | Every page becomes an optimised image at 110 dpi | Scanned documents and forms |
Tips and good to know
- Text-only PDFs (like contracts typed in Word) are already small and won't shrink much — that's normal.
- Need the file under a specific size such as 200 KB? The PDF Size Reducer keeps trying until it gets there.
- Always keep your original: Strong compression makes text unsearchable in the copy.
- Scanning again at 150–200 dpi in grayscale produces much smaller files than 600 dpi colour scans.