How to Run OCR on a Scanned PDF
Make scanned documents searchable and selectable. Choose from 20+ languages, adjust recognition sensitivity, and download the text-enabled PDF.
Introduction
OCR PDF is a free online tool that makes scanned PDFs searchable and selectable using Optical Character Recognition (OCR) technology. When you scan a paper document, the result is an image-based PDF — you can see the text but can't search, copy, or edit it. OCR solves this by recognizing text characters in the image and adding a searchable text layer. Unlike other OCR services that upload your documents to cloud servers, PDFly runs OCR entirely in your browser using Tesseract.js and WebAssembly. Your scanned documents never leave your device, ensuring complete privacy for sensitive records. The tool supports 20+ languages and offers three recognition sensitivity levels. There are no file size limits, no daily usage caps, no watermarks, and no account required. This tutorial covers every OCR option, with pro tips for maximum accuracy, troubleshooting, and FAQs.
Step-by-Step Guide
Upload Your Scanned PDF
Drag and drop your scanned PDF onto the workspace, or click to browse and select it.
Select Document Language
Choose the primary language from 20+ supported languages. This helps the OCR engine recognize characters accurately.
Adjust OCR Settings
Choose recognition sensitivity: "Standard" for clear scans, "High" for lower quality, or "Maximum" for difficult documents.
Run OCR and Download
Click "Run OCR." Processing may take a few minutes for large documents. Download the searchable PDF.
Pro Tips & Best Practices
Higher quality scans produce better OCR results — 300 DPI or higher is ideal.
For multi-language documents, select the primary language.
After OCR, use the PDF to Text tool to extract recognized text.
OCR works best on black-and-white or grayscale scans.
Common Use Cases
Digitize Old Documents
Make old paper documents searchable by scanning and running OCR.
Search Scanned Archives
Convert scanned archives into searchable PDFs for easy information retrieval.
Extract Data from Forms
OCR scanned forms to make text selectable and copyable for data entry.
Key Features
20+ Languages
Recognize text in over 20 languages.
Adjustable Sensitivity
Standard, High, or Maximum recognition modes.
Searchable Output
Text becomes searchable, selectable, and copyable.
100% Private
All OCR processing happens in your browser.
Frequently Asked Questions
Processing time depends on document size and scan quality. A 10-page document typically takes 30-60 seconds.
Accuracy depends on scan quality, font clarity, and language. Clear, high-resolution scans typically achieve 95%+ accuracy.
OCR is optimized for printed text. Handwritten text recognition is significantly less accurate.
Common Issues & Solutions
OCR accuracy is low
Ensure you selected the correct document language. Higher quality scans produce better results — 300 DPI or higher is ideal. Try Maximum sensitivity mode for difficult documents. For handwritten text, OCR accuracy is significantly lower.
OCR is taking very long
OCR is computationally intensive. A 10-page document typically takes 30-60 seconds. A 50-page document may take 2-3 minutes. Close other browser tabs and be patient — the process will complete.
Recognized text has garbled characters
This usually means the wrong language was selected. Re-run OCR with the correct language. For documents with multiple languages, select the primary language. Low-quality scans also cause garbled output.
Can't search the output PDF
Make sure you're opening the output PDF in a modern PDF viewer that supports text layers. Try Adobe Acrobat Reader or any browser's built-in PDF viewer. Very old PDF readers may not support searchable text layers.
Ready to Try OCR PDF?
Put this tutorial into practice right now. OCR PDF is free, browser-based, and requires no signup.
Open OCR PDF