What makes scanned PDFs different?
Scanned PDFs compress differently because file size is dominated by images.
Scanned PDFs are basically images
That’s why they’re usually huge. Compression mainly reduces image resolution/quality to shrink the file.
Compact first, Rasterize if strict limit
Try Compact if you want the PDF to behave like a normal PDF. If you must hit a strict size (1MB/2MB), use Rasterize and lower DPI/quality step-by-step.
Tradeoff is real
Reducing image resolution/compression lowers size but can affect clarity—especially small text. Aim for “readable” not “perfect.”
Best workflows for scanned PDFs
The goal is “readable + small enough.” Don’t over-compress and ruin small text.
For readable scans (recommended)
Compact first → if still large, Rasterize slightly. Stop as soon as text remains readable at 100% zoom.
For strict upload limits
Use Rasterize and lower quality/DPI step-by-step until you hit the target (1MB/2MB/5MB).
For photo scans
Photo-heavy scans compress more than text-heavy scans, but clarity can drop faster—use small steps.
For multi-page scans
If the portal allows it, splitting a 50-page scan into parts can preserve readability better than aggressive compression.
How to compress a scanned PDF online (3 steps)
1) Upload your scanned PDF
Upload the scanned PDF. The file is transferred over an encrypted TLS connection for processing.
2) Choose Compact or Rasterize
Start with Compact. If you need a much smaller file, use Rasterize and reduce quality/DPI step-by-step.
3) Download & verify readability
Download the smaller PDF and zoom to 100% to confirm small text is still readable.
Smart PDF Compression
- Guaranteed Size Reduction
- Smart Mode: Preserves Text (Vectors)
- Force Mode: Flattens to printable images
Drop your PDF here
We'll analyze it to see how much we can compress.
Compress scanned PDF — FAQs
How do I compress a scanned PDF online?
Upload your scanned PDF, start with Compact, and if the file is still too large, switch to Rasterize and reduce quality/DPI step-by-step until you reach the size you need.
Why are scanned PDFs so large?
A scanned PDF is mostly images (each page is like a photo). Large images make the file size huge compared to normal text-based PDFs.
Will compressing a scanned PDF reduce clarity?
It can. Size reduction usually comes from compressing/downsampling images, which can reduce sharpness—especially small text. Reduce in small steps and stop when it remains readable.
What mode should I use for scanned PDFs?
If you need maximum reduction, use Rasterize. If you want better “PDF behavior” and lighter changes, start with Compact and only use Rasterize if needed.
Can I make it under 1MB / 2MB?
Often yes, but it depends on pages and scan quality. For strict limits, use the target pages and Rasterize with lower quality/DPI step-by-step.
Is my scanned PDF uploaded to your servers?
Your PDF is transferred over an encrypted TLS connection to our compression backend and Adobe PDF Services for processing. Avoid uploading extremely sensitive documents to any online service.
Does it work on iPhone and Android?
Yes. Open this page in Safari (iOS) or Chrome (Android) and compress scanned PDFs without installing an app.
If clarity gets bad, what should I do?
Try compressing less, removing unnecessary pages, or splitting the PDF. For tiny-text documents, aggressive compression can make text unreadable.