How to make a scanned PDF searchable with OCR

A scanned PDF is really a set of pictures. You can read it, but you can’t search it, select a sentence or copy a figure out of it. OCR — optical character recognition — fixes that by reading the words in the images and adding them to the file as a hidden text layer.

How to OCR a PDF

1. Open OCR PDF and select the scanned document.
2. Choose the language the document is written in. This matters: it tells the recognizer which letters and words to expect.
3. Leave “Skip pages that already have text” on if the PDF is a mix of scanned and digital pages.
4. Click Recognize text. Each page takes a few seconds.
5. Download the searchable PDF, and the .txt file if you want the text on its own.

The pages look exactly the same as before. The difference is that Ctrl+F (⌘F on a Mac) now finds words, and you can select and copy text.

Getting accurate results

• Resolution: 300 dpi is the sweet spot for text. Below 200 dpi small print starts to fail.
• Straight, flat pages: tilted or curled pages confuse recognition. If you photograph pages, hold the phone parallel to the paper.
• Contrast: dark text on a plain light background works best. Remove shadows by scanning in even light.
• The right language: accented letters are recognized far better when the right language is chosen.

What to do next

Once a PDF has text, the other text tools work on it too: Search PDF, PDF to text, Compare PDF, and the AI Summarize PDF.

OCR is very good but not perfect. For numbers that matter — amounts, account numbers, dates — check the recognized text against the page.