To summarize a text or a PDF with AI, upload the file to an AI chat such as ChatGPT, Claude or Gemini, say what you need the summary for and ask for the page each point comes from. That gives you the key points of a long document in about a minute. Anything that matters legally or financially, meaning deadlines, amounts and obligations, you still check in the original.
I work with Claude every day. My fourteen AI employees run on Claude Team, some also on open models or through the API. The file limits in this article come from the help pages of OpenAI, Anthropic and Google, retrieved on 27 October 2026. All the basics about AI are collected on my AI Basics page.
Three steps to a useful summary
1. Upload the document. In all three chats you attach the file directly to your message, in Claude for example via the plus button or by dragging it into the chat window. All three accept PDF, Word and plain text files. Pasting the text in also works, but for long documents the file is easier to handle.
2. Say what you need the summary for. "Summarize this" gets you a general overview of the contents. A purpose is far more useful: for whom, for what, how long. An example, made up: a carpenter receives a new lease for his workshop, twenty pages. He wants to know what he is committed to from day one.
"Summarize this lease for me as the tenant. I need: every obligation I have, every deadline with its date, every cost apart from the rent and anything that differs from the usual. One page at most, as a list. Give the PDF page for each point. If the lease says nothing about a point, say so."
3. Ask for page references. With the page number you can look up each point in the original in ten seconds. For long documents, Anthropic recommends going one step further: have the AI pull out the relevant passages word for word first and only then answer. That way it relies on the actual text rather than a memory of it. A practical tip from Anthropic: use the page number your PDF viewer shows, not the number printed at the bottom of the page.
The result is a working list, not an expert opinion. For a contract, it replaces neither reading the important passages yourself nor legal advice when a lot of money is at stake.
How long can the document be?
Every provider sets its own file limits. In ChatGPT, the amount of text in tokens counts too. A token is a small piece of text in AI, such as a word or a syllable. These are the values on the help pages (as of 27 October 2026):
Claude has a detail that matters for beginners: PDFs of up to 100 pages are read with text and images, including tables, charts and graphics. For 101 to 1,000 pages, Claude reads the text only. From Word and text files Claude only extracts the text anyway; it does not see embedded images there. For large files, Anthropic suggests splitting them into smaller sections.
Why long documents still have limits
Being able to upload a file does not mean the AI keeps every page equally in view. Everything the AI has in front of it at a given moment is called context, and its size is limited. When the context is very full, a model is more likely to miss details. I explain exactly how that works in Context and Context Windows in AI Explained.
Two habits help:
- One chat per document. If you discuss three contracts in the same chat, the AI is more likely to mix up what was where.
- Document first, question last. Anthropic recommends putting long documents at the top of the message and the question at the end. In tests this improved response quality by up to 30 percent, especially with several documents. If you upload a file and write your question below it, you are already doing it right.
Which texts to summarize and which belong elsewhere
Good candidates are documents you do not want to read in full but whose core you need: contracts, a supplier's terms and conditions, funding guidelines, long email threads, specialist articles, manuals. You can also have two versions compared: "What changed between the old and the new contract?"
Conversations have their own route. If you need minutes from a meeting, read Automatic Meeting Minutes with AI or Have Minutes Written: ChatGPT, Teams. Those are about recordings and transcripts; this article is about finished documents.
What to watch out for
- Check deadlines and amounts yourself. An AI can leave out a point or copy a number wrongly. The page reference makes checking quick. Why AI sometimes invents things is explained in AI Hallucinations: Why AI Makes Things Up.
- Ask about gaps. A summary shows what is in the document. Also ask: "What is missing from this contract that such contracts usually cover?" The answer is a pointer, not a review.
- Check confidential documents first. Contracts with client names, salaries or health data do not belong in an AI chat unchecked. What you can show an AI is covered in AI and Privacy: What the AI Gets to See.
- A deleted chat is not a deleted file. In ChatGPT, a file can remain saved in the Library even if you delete the chat. You delete it there.
Frequently asked questions
Can ChatGPT summarize PDFs?
Yes. ChatGPT accepts PDF, Word, text files, spreadsheets and presentations, on the free and on paid plans. According to OpenAI, the free plan allows at most three uploads per day. Claude and Gemini can summarize PDFs as well.
How long can a PDF be for the AI?
In Claude up to 1,000 pages, with images and graphics only read up to 100 pages. In ChatGPT the limit depends on file size and on 2 million tokens of text per file. In Gemini it is up to 100 MB per file. The longer the document, the more important page references and targeted questions become.
Can the AI read scanned documents?
In Claude it depends on length: PDFs of up to 100 pages are analysed including their visual content, for 101 to 1,000 pages only the text. My conclusion: a long scan without a text layer is then practically empty for Claude, so split it into sections of up to 100 pages. With poor scans, handwriting or skewed pages, check the result especially carefully.
Is an AI summary as good as reading it yourself?
For an overview it is fast and often good enough. For decisions it is not. Read the passages that matter in the original; that is what the page references are for.
Can I summarize several documents at once?
Yes. Claude takes up to 20 files per chat, Gemini up to 10 per prompt. That is handy for comparing two versions. For unrelated documents, use a separate chat for each one.
Where to go from here
Take a document that has been sitting unread in your inbox for weeks and try the brief from step 2 with your own purpose. Then check three points in the original using the page references. How to go the other way and turn bullet points into a text is in Writing with AI: A Beginner's Guide. If your documents are spreadsheets rather than texts, continue with AI for Excel: Formulas, Analysis, Limits. How others work through their documents with AI is what we discuss in my community Claude Practitioners.
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