To chat with a PDF, upload it to an AI assistant such as ChatGPT, Claude or Gemini and ask questions in plain language: “What are the payment terms?”, “Summarize chapter 3”, “Which table shows the 2025 revenue?” All three work on their free plans. The differences are in file limits, whether charts and scanned pages are read, and how reliably the answer points to the right page.
Below are the limits for each tool, a short workflow and the prompts that give the most accurate answers. Limits were checked in each vendor’s help center on 21 October 2026.
The quickest way to chat with a PDF
- Open ChatGPT, Claude or Gemini and sign in.
- Click the paperclip or plus icon next to the message box, or drag the PDF into the chat.
- Wait for the upload to finish, then ask your first question.
- Ask the assistant to quote the passage or give the page number for each answer, so you can check it.
That last step matters more than the choice of tool. Every model can misread a document or fill gaps with plausible guesses, and quotes make mistakes easy to spot.
File limits compared
| Tool | Max file size | Files at once | How PDFs are read | Source |
|---|---|---|---|---|
| ChatGPT | 512 MB, and up to 2M tokens of text per file | Free: 3 uploads per day; paid: up to 80 files every 3 hours | Text only on all plans except Enterprise, which also reads images inside PDFs | OpenAI |
| Claude | 500 MB | 20 per chat | Up to 100 pages: text plus charts and images; 101 to 1,000 pages: text only; over 1,000 pages: rejected | Anthropic |
| Gemini app | 100 MB | 10 per prompt | Reads PDFs; 1M-token context on Google AI Pro and Ultra, smaller on Free | |
| Gemini Notebook (formerly NotebookLM) | 200 MB, up to 500,000 words per source | Many sources per notebook | Answers only from your sources, with citations to the passage |
What this means in practice:
- For a long report with charts, Claude reads the visuals as long as the PDF is 100 pages or less. ChatGPT on consumer plans discards images inside PDFs, so a question about a chart may fail.
- For a stack of documents you return to, such as course readings or a set of contracts, Gemini Notebook is built for it: every answer links to the source passage.
- On free plans, ChatGPT’s three uploads a day can be the real limit.
Which tool to use for which document
Contracts and legal documents
Use Claude or Gemini Notebook. Long context helps here because clauses refer to each other. Ask for exact quotes: “List every clause about termination, quote it word for word, and give the section number.” Treat the output as a reading aid, not legal advice.
Research papers
Use Claude for papers with figures under 100 pages, or Gemini Notebook for several papers at once. Good prompts: “Explain the method in plain language”, “What are the limitations the authors admit?”, “Which figure supports the main claim, and what does it show?”
Reports and financial statements
Tables are where models make the most mistakes. Ask the model to copy the table first (“Reproduce table 4 as a markdown table”) and check it against the PDF before asking questions about the numbers. For spreadsheet work, upload the original Excel or CSV file if you have it; it is far more reliable than a PDF table.
Books and manuals
Claude’s 1,000-page text limit and Gemini Notebook’s 500,000 words per source cover most books. Ask by chapter rather than the whole book at once, and ask for the page or section so you can verify.
Scanned PDFs
A scanned PDF is a picture of text. If you can’t select the text in your PDF reader, the AI needs to run text recognition. Claude reads page images for PDFs up to 100 pages; for longer scans, run OCR first in a PDF editor and upload the result.
Prompts that work well with PDFs
Copy these and change the bracketed parts.
- “Summarize this document in 5 bullet points for [a busy manager / a student / a client]. Add the page number after each point.”
- “List every date, deadline and amount of money in this document, with the page for each.”
- “What does this document say about [topic]? Quote the relevant sentences. If it says nothing, say so.”
- “Explain section [X] as if I had no background in [field].”
- “Create 10 quiz questions from chapters [1 to 3] with answers and page references.”
- “Compare these two PDFs. What changed between version 1 and version 2?”
- “What questions should I ask before signing this? Base them only on the text.”
The phrase “if it says nothing, say so” reduces invented answers. Models try to be helpful and will sometimes answer from general knowledge when the document is silent.
How to avoid wrong answers
- Ask for quotes and page numbers, then check two or three of them.
- Split very long documents. Even with large context windows, details in the middle of a long file are easier to miss.
- Start a new chat for a new document so the model doesn’t mix sources.
- Be careful with numbers in tables and with negatives (“shall not”, “except”).
- Don’t upload confidential documents to a consumer account unless your employer allows it. Business plans of ChatGPT, Claude and Gemini offer stronger data terms.
Dedicated “chat with PDF” apps
Specialist tools such as ChatPDF and Adobe Acrobat’s AI Assistant focus only on documents. They can be convenient if you already work in Acrobat or want a simple single-purpose interface. For most people the general assistants above are enough and come with free plans. If you want to try several models on the same document, an all-in-one AI app can help.
FAQ
Can ChatGPT read PDFs?
Yes. Upload the PDF and ask questions. On Free, Go, Plus and Pro plans ChatGPT reads the text but ignores images inside the PDF; only Enterprise reads the visuals. Free users can upload three files a day.
What is the best AI to chat with a PDF?
For a single long document with charts, Claude is a strong choice because it reads visuals in PDFs of up to 100 pages. For many documents with source citations, Gemini Notebook is built for that job. ChatGPT works well for text-heavy PDFs.
Is it free to chat with a PDF?
Yes, ChatGPT, Claude, Gemini and Gemini Notebook all let you upload PDFs on free plans, with daily or usage limits.
Can AI read a 500-page PDF?
Claude reads PDFs of up to 1,000 pages as text, and Gemini Notebook accepts sources up to 500,000 words. ChatGPT accepts files with up to 2 million tokens of text. For best accuracy, ask questions about specific chapters.
Conclusion
Chatting with a PDF works in every major AI assistant. Pick Claude for documents with charts, Gemini Notebook for several sources with citations, and ChatGPT for text-heavy files, and always ask for quotes with page numbers. For more on choosing an assistant, see how to use Claude and our AI models comparison.