How to summarize a document or a video with AI, step by step

To summarize a document with AI, upload the file (or paste the text) into an assistant, say who the summary is for and what it is for, then ask it to point to the passages it relies on. This tutorial walks you through a five-step method that works for a PDF, a web page, meeting notes or a video.

What you need before you start

• An AI assistant that accepts file uploads, such as ChatGPT, Claude, Gemini, Le Chat or Copilot. An AI assistant is a program you write to in plain language and that answers by writing text.
• The document, as a PDF, Word or text file, or the link to a web page. For a video, its transcript if possible.
• A clear goal: why do you want this summary? To make a decision, to study, to brief someone?
• Five minutes to review, because you remain responsible for what you take away from it.

Here are the main assistants, with the features listed on each company’s website, including file uploads:

Assistant	Free	Paid from	Web search	Agent mode	Voice	Images
ChatGPT	Limited	$8/mo	Yes	Yes	Yes	Yes
Claude	Limited	$20/mo	Yes	Yes	—	—
Gemini	Limited	€4.99/mo	Yes	—	Yes	Yes
Le Chat (Mistral Vibe)	Limited	$5.99/mo	Yes	Yes	Yes	Yes
Microsoft Copilot	Limited	$9.99/mo	Yes	—	Yes	Yes
Perplexity	Limited	$10/mo	Yes	Yes	—	Yes

An empty cell means the company does not specify the feature, not that it is missing.

Step 1: prepare and clean up the document

Before you upload anything, skim the document for sensitive information: names, addresses, account or policy numbers, health details. Hide or delete anything the summary does not need.

If the document is a scan (a picture of a page), make sure the text is readable. Multimodal assistants can read images, but a blurry or tilted scan raises the risk of mistakes. When you can, use the original PDF.

For a very long document, keep one technical limit in mind: the context window, the amount of text a model can take into account at once. It is measured in tokens, which are pieces of words. Beyond that limit, the assistant may ignore part of the text without always telling you.

Step 2: upload the document and give context

Attach the file with the dedicated button (often a paperclip or a ”+”), or paste the text. Then write your request, called a prompt. A good summary prompt states four things:

1. Who it is for: “for me, and I’m not a lawyer”, “for my team”.
2. What it is for: deciding, studying, replying to a letter.
3. The format: five key points, one paragraph, a table.
4. The length: “in under 150 words”.

Example: “Here is my apartment lease. Summarize in five points what matters to me as the tenant: term, rent, fees, move-out conditions and maintenance duties. For each point, tell me the page or clause it comes from.”

Step 3: ask for references in the text

This is the most important step. An assistant can produce a hallucination: stating with confidence something that is not in the document. When you ask it to cite the page, clause or exact sentence, you can check in seconds.

Also add: “If a piece of information is not in the document, say so instead of guessing.” This instruction reduces made-up answers, but it does not eliminate them.

Check yourself The assistant tells you your lease requires one month's notice. What do you do?

Ask for the exact clause where that notice period appears, then open the lease at that spot and read the sentence yourself. A notice period is binding: never rely on the summary alone for it.

Step 4: dig deeper with follow-up questions

The first summary is only a starting point. Then ask targeted questions:

• “What in this document could cost me money?”
• “Which dates or deadlines should I write down?”
• “Explain section 4 in plain English.”
• “What does this summary leave out?”

That last question is handy: it makes the assistant flag what it treated as minor, so you can decide for yourself whether it really is.

Step 5: check the passages that matter

In the original document, reread everything about money, dates, your rights and your obligations. Compare it with the summary. If you spot a mistake, tell the assistant: it will revise the rest of its answer with your correction in mind.

Videos and meetings

For a video, the safest method goes through text. Many platforms, including YouTube, show a transcript below the video when captions exist. Copy it, paste it into the assistant and follow the same steps, this time asking for timestamps (“at what point in the video?”) rather than pages.

Some assistants accept a video link or file directly, depending on the company and the plan. That is convenient, but make sure it actually processed the whole video, not just the title or description.

For a meeting recording or a voice memo, the transcript relies on speech recognition, which turns speech into text. Names, numbers and technical terms are the most often garbled: check them before asking for a summary.

Type of content	How to send it	What to watch
PDF or Word document	Attachment	Scanned pages, complex tables
Web page	Link or copied text	Ads and menus mixed into the text
Video	Pasted transcript, or link if supported	Only part of the video processed
Meeting or audio	Transcript	Misheard names and numbers
Very long report	Chapter by chapter	Context window exceeded

Very long documents: work in chunks

Recent models accept large amounts of text. According to models.dev, as of October 22, 2026, several models list a context window of about one million tokens through their API:

Context window (tokens)

• Claude Sonnet 5.51 M
• Gemini 4 Argon1.05 M
• GPT-6.1 Sol1.05 M
• Mistral Large 41.05 M
• DeepSeek V4.1 Flash 10171.05 M

To estimate the size of your text, our context window tool shows whether a document fits in one go in a given model.

Keep confidential documents private

Whatever you upload goes to the company’s servers. According to the companies’ websites, as checked on October 22, 2026, settings vary from one assistant to another.

For work documents, your employer’s policy comes first: some companies forbid uploading internal files to a public assistant. For official letters and forms, our guide to using AI for paperwork safely covers the precautions.

What comes after the summary?

A good summary is often the basis for an action: replying to a letter, preparing for a meeting, studying for a test. To write the reply, follow our tutorial on writing emails, letters and résumés with AI. If the document is in another language, ask for the summary in English directly, then read our tips to learn a language with AI. You will find more ideas in our list of everyday ways to use AI.