How to Summarize and Translate Long PDFs with AI (and Check the Results)

How the AI tools work

When you use AI Summarizer, Translate PDF, Chat with PDF, AI Proofreader, AI PDF Reader, or Compare PDF, your browser first extracts the text from the PDF. That text — not the file itself — is sent through our server to an AI language model, which writes the answer.

That has two consequences. First, the tool only sees text: charts, images, and layout are invisible to it, and a scanned PDF with no text layer has nothing to read until you run OCR PDF. Second, your text leaves your device, so avoid these tools for documents you must not share with a third-party service. Our privacy checklist covers that decision.

The length limits you need to know

Language models can only read a limited amount at once, so each tool uses only the first part of long text:

• AI Summarizer and AI PDF Reader: about the first 30,000 characters.
• Chat with PDF and Translate PDF: about 28,000 characters.
• AI Proofreader: about 25,000 characters.
• Compare PDF: about 15,000 characters from each document.

As a rough guide, 30,000 characters is about 5,000 words — around ten pages of ordinary text. Anything beyond the limit is not read, and the tools do not warn you loudly, so a summary of a 100-page report is really a summary of its first ten pages unless you split it.

A workflow for long documents

1. 1If the PDF is a scan, run OCR PDF first so there is text to read.
2. 2Split it into chunks of about eight to ten pages with Split PDF (enter ranges such as “1-10, 11-20, 21-30”), or pull out the chapters you care about with Extract Pages.
3. 3Run the AI tool on each chunk and keep the outputs together.
4. 4Read the part summaries in order. For a translation, translate chunk by chunk and join the results.

Checking the results

• Verify numbers, names, dates, and quotes against the original. These are where AI errors cluster, and where mistakes matter most.
• Ask for the source. In Chat with PDF, ask the model to quote the passage it used, then find that passage in the document. Be wary of confident answers about things the document does not cover.
• Translations: machine translation is good for understanding the gist and drafting, but it can mistranslate idioms, names, and technical terms. Have a qualified human check anything official — contracts, legal filings, medical information.
• Comparisons: the comparison is an AI-written list, not an exact text difference. It can miss a single changed number, so check critical clauses yourself.
• Proofreading: read each correction before accepting it. AI sometimes “fixes” deliberate choices such as names and technical terms.

Using AI tools responsibly

AI summaries and translations are aids, not authorities. Do not make legal, medical, or financial decisions from an AI summary alone. If your school, employer, or publisher has rules about AI-assisted work, follow them and disclose AI use where it is required. Each tool is also limited to 10 requests per minute per visitor; if you see a “too many requests” message, wait a minute and try again.