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Open the FilesDoctor Compress PDF tool, upload your file, choose the right compression option, and download the smaller PDF.
Open Compress PDF ToolWhy Scanned PDFs Are So Large
A scanned PDF is usually made of images. Each page may contain a full-page scan, which makes the file size much larger than a normal text-based PDF.
If the scan resolution is high or the pages are in color, the PDF can become very large.
How to Compress Scanned PDF Online
Use these steps to reduce a scanned PDF file size with FilesDoctor.
Open the Compress PDF tool
Go to FilesDoctor and open the Compress PDF tool.
Upload your scanned PDF
Select the scanned document, certificate, form, or ID file you want to reduce.
Choose a realistic file size
For scanned PDFs, start with 500KB or 1MB if readability is important.
Compress the file
Click Compress & Optimize PDF to create a smaller scanned PDF.
Check the final PDF
Zoom in and check names, dates, signatures, stamps, and small text before uploading.
Best Size for Scanned PDF Files
| Scanned PDF Type | Recommended Size | Reason |
|---|---|---|
| Single-page certificate | 200KB to 500KB | Usually enough if the scan is clean. |
| Signed form | 500KB to 1MB | Helps keep signatures readable. |
| ID or KYC document | 300KB to 1MB | Details must stay clear. |
| Multi-page scanned document | 1MB or higher | More pages need more space. |
| Photo-based PDF | 1MB or higher | Better for image clarity. |
How to Keep Scanned PDF Clear
- Use 500KB or 1MB instead of 100KB when possible.
- Scan documents cleanly before creating the PDF.
- Remove extra blank pages before compression.
- Use grayscale if color is not required.
- Check small text, QR codes, stamps, and signatures after compression.
- Keep the original scan safe before compressing.
Should You Use OCR for Scanned PDFs?
If your scanned PDF contains text that you want to search or copy, OCR can help. Compression reduces file size, while OCR makes scanned text searchable. For some documents, you may need both.
Compress the PDF when file size is the problem. Use OCR when the scanned text is not selectable or searchable.
FAQ
Why are scanned PDFs so large?
Scanned PDFs are image-based. Each page is stored like a picture, so the file size is usually larger than a normal text PDF.
Can I compress a scanned PDF to 100KB?
Sometimes, but the file may become unclear. For scanned documents, 500KB or 1MB is often better.
How do I keep signatures readable?
Avoid very strong compression. After compression, zoom in and check the signature before uploading.
Should I use OCR before or after compression?
Use OCR if you need searchable text. Use compression if you need a smaller file. The best order depends on your workflow.
Can I compress scanned certificates online?
Yes. Upload the scanned certificate to FilesDoctor Compress PDF and choose a target size that keeps the text readable.
Compress your PDF now
Reduce PDF file size for online forms, WhatsApp, email, job applications, and document uploads.
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