This is a one-page reference for prompting NotebookLM, Google's source-grounded research tool built on Gemini 3. NotebookLM answers only from the sources you add, with inline citations to the exact passage, so it rarely hallucinates — the whole game is giving it good sources and a precise prompt. Below you get the grounded-prompt formula plus copy-paste tables of source types, Studio outputs, and every Audio and Video Overview format and style.
New to it? Start with the best NotebookLM prompts roundup, then read how to prompt NotebookLM for research and keep the prompt templates handy while you work.
The NotebookLM prompt formula
A strong NotebookLM prompt names five things: the task, which sources to use, the output format, a citation rule, and an uncertainty rule. Because answers are grounded in your sources, spelling these out is what turns a vague reply into a verifiable one.
| Part | What to write |
|---|---|
| Task | The exact job — summarize, compare, extract, outline, quiz me. |
| Sources | Which sources to use — "using only the selected sources" or "across all sources." |
| Format | How to return it — a table, bullets, a numbered list, a one-page brief. |
| Cite rule | "Cite the source and page for every claim" or "quote the exact line." |
| Uncertainty rule | "Say if the sources don't cover this rather than guessing." |
Example prompt that uses all five parts:
Using only the selected sources, summarize the main argument of each document in 2-3 sentences, then build a table comparing them on methodology, key finding, and limitation. Cite the source and page for every claim, and quote the exact line where a finding is stated. If the sources disagree, show both positions. If something isn't covered by the sources, say so instead of guessing.Why it works: it fixes the task, scopes the sources, sets the format, forces citations, and tells NotebookLM to flag gaps — the five levers that make a grounded answer trustworthy.
Source types you can add
NotebookLM accepts a wide range of source types, and each source can be very long — a whole book-length PDF or a multi-hour transcript still counts as one source. The best results come from clean, primary documents.
| Source type | Notes / limits |
|---|---|
| Best all-rounder. Reports, papers, books, filings. Text-based PDFs read cleanly; scanned pages depend on the text layer. | |
| Google Docs | Imported directly from Drive. Re-sync to pull in edits made after you added it. |
| Google Slides | Pulls in slide text and structure — good for decks and lecture slides. |
| Website URL | Ingests the page's readable text. Quality depends on the page; paywalled or JS-heavy pages may import poorly. |
| YouTube link | Uses the video's transcript, so it works best when captions exist and are accurate. |
| Pasted text / Markdown | Paste notes, snippets, or Markdown directly. Handy for content that isn't a file yet. |
| Audio file | Transcribed automatically — add recordings, interviews, or voice memos and query the transcript. |
Source limits: free notebooks hold up to 50 sources; paid plans raise the cap to 300 sources per notebook. You can select or deselect individual sources before a query to focus the answer on just the ones that matter.
Studio outputs cheat sheet
Studio turns your sources into finished artifacts, not just chat answers. Pick the output that matches how you want to consume or share the material.
| Output | What it's best for |
|---|---|
| Audio Overview | A podcast-style discussion of your sources you can listen to hands-free. |
| Video Overview | A narrated visual walkthrough with on-screen text and imagery. |
| Study Guide | Key concepts, questions, and terms to revise from before an exam. |
| Briefing Doc | A tight executive summary of the essentials across your sources. |
| FAQ | The likely questions and grounded answers about your material. |
| Timeline | A dated sequence of events pulled from the sources. |
| Data Table | Structured rows and columns extracted from the sources. |
| Slide Deck | A presentation drafted from your material, ready to refine. |
| Flashcards | Term-and-definition cards for active recall and memorization. |
| Quiz | Practice questions to test your understanding of the sources. |
| Mind Map | A branching visual map of how the ideas connect. |
| Infographic | A single visual summary of the key points (added March 2026). |
| Custom Report | Any report format you describe — you set the structure and focus. |
Audio Overview formats & controls
An Audio Overview is a generated audio discussion of your sources. Pick a format for the tone, then use the controls to set length, complexity, and language.
| Format | When to use |
|---|---|
| Deep Dive | The default two-host conversation — a full, engaging discussion of the material. |
| Brief | A quick summary when you want the gist in a couple of minutes. |
| Critique | An expert-style review that evaluates and pressure-tests the sources. |
| Debate | Two hosts argue opposing sides — good for contested or two-sided topics. |
Controls: set length (Shorter / Default / Longer), adjust complexity for the audience, choose from 80+ languages, and use Interactive mode to talk to the hosts live and ask them questions mid-episode. All formats are steered by the "What should the AI hosts focus on?" focus box.
Example focus-box prompt (paste into the focus box before generating):
Focus on the practical takeaways for a small-business owner. Skip the background theory and spend most of the episode on the specific steps, costs, and trade-offs described in the sources. Keep the language plain, define any jargon, and end with the three things a listener should do first.Video Overview formats & styles
A Video Overview is a narrated visual walkthrough of your sources. Choose a format for the depth, then a visual style for the look.
| Format | When to use |
|---|---|
| Explainer | A fuller narrated walkthrough that teaches the material in depth. |
| Brief | A short visual summary for a quick overview or a shareable clip. |
Visual styles: Classic, Whiteboard, Kawaii, Watercolor, Papercraft, Anime, Heritage, and Retro Print. Match the style to your audience — Whiteboard for teaching, Classic for work, Anime or Kawaii for lighter or younger audiences. Like audio, video is steered by the same focus box.
Example focus-box prompt for a Video Overview:
Make an Explainer that walks through the process described in the sources step by step. Show each stage clearly on screen with its label, keep the narration concise, and use the exact terms from the sources. Highlight the two most common mistakes the sources mention. Aim it at a beginner who has never done this before.Chat modifiers & phrases that work
Small phrases dropped into a chat prompt reliably change what NotebookLM gives you. These are the ones worth memorizing.
| Phrase | Effect |
|---|---|
| cite the source and page | Forces a specific citation on every claim, not just a chip. |
| using only the selected sources | Restricts the answer to the sources you've ticked, ignoring the rest. |
| say if the sources don't cover this | Prevents guessing — it flags gaps instead of filling them. |
| as a table | Returns structured rows and columns instead of prose. |
| compare across all sources | Pulls the answer from every source and contrasts them. |
| quote the exact line | Returns verbatim text so you can verify wording, not a paraphrase. |
| save to Notes | Keeps a useful answer in the notebook to reuse or turn into a source. |
Example chat prompts that stack these modifiers:
Using only the selected sources, list every recommendation the authors make. Present it as a table with columns: recommendation, the reason given, and the source and page. Quote the exact line for each. If a recommendation appears in more than one source, note which ones. Say if any section has no clear recommendation rather than inventing one.Compare across all sources how each one defines [key term]. Show the definitions side by side as a table, quote the exact line for each, and cite the source and page. Flag any place where the definitions conflict, and say if a source doesn't define the term at all.Using only the selected sources, build a dated timeline of the key events. For each entry give the date, what happened, and the source and page, quoting the exact line. If two sources disagree on a date, show both and note the conflict. Say if any event has no date in the sources.Once a prompt lands close, tighten it the way you would brief a research assistant — name the exact sources, set the format, and add the citation and uncertainty rules. For more, read how to prompt NotebookLM for research and grab a starting point from the prompt templates.
Frequently Asked Questions
How many sources can I add to a NotebookLM notebook?
Free notebooks hold up to 50 sources, and paid plans raise that to 300 sources per notebook. Each source can be very long — a full book-length PDF, a long transcript, or a large Google Doc all count as a single source. Because NotebookLM answers only from what you add, more sources means broader coverage, but you can select or deselect individual sources to focus a single query on just the ones that matter. For most projects you will hit the quality of your sources long before you hit the numeric limit.
What are the best source types to add to NotebookLM?
The most reliable sources are ones with clean, extractable text: PDFs, Google Docs, Google Slides, pasted text, and Markdown. Website URLs and YouTube links work well when the page or video has a good transcript, and audio files are transcribed automatically. For grounded answers, prefer primary documents — reports, papers, official filings, and your own notes — over thin web pages. Mixing a few authoritative sources beats dumping in dozens of low-quality ones, because every answer and Studio output is built only from what you provide.
Should I use an Audio Overview or a Video Overview?
Use an Audio Overview when you want to listen — commuting, walking, or reviewing material hands-free — and pick Deep Dive for a full discussion or Brief for a quick summary. Use a Video Overview when visuals help, such as explaining a process, showing structure, or sharing something that benefits from on-screen text and imagery. Video adds visual styles like Whiteboard, Anime, or Papercraft, while Audio adds Interactive mode so you can talk to the hosts live. Both are steered by the same focus box, so the choice comes down to whether your audience will watch or listen.
How do I force NotebookLM to cite its sources?
NotebookLM cites automatically — most chat answers include inline citation chips that jump to the exact passage in the source. To make citations tighter, add instructions to your prompt like "cite the source and page for every claim" or "quote the exact line you are drawing from." You can also click any citation to open the original passage and verify it. Because the tool is source-grounded, it rarely invents facts, but the citations are there so you can confirm each claim against the underlying document.
Is NotebookLM free?
Yes, NotebookLM has a free tier that includes up to 50 sources per notebook plus daily limits on chat queries and Studio outputs like Audio Overviews. Paid plans raise the ceiling to 300 sources per notebook and higher daily usage limits, along with additional features for heavier users. For occasional research and study, the free tier is generous. If you build many notebooks, generate lots of Audio or Video Overviews, or need the larger source cap, the paid tier is worth it.
Does NotebookLM use information from outside my sources?
By design, NotebookLM answers from the sources you add to a notebook, with inline citations back to the exact passages, which is why it rarely hallucinates. It runs on Gemini 3, so the underlying model has broad general knowledge, but the product keeps chat answers grounded in your material rather than pulling in outside facts. If your sources do not cover something, a well-written prompt should tell it to say so rather than guess. Adding a line like "answer only from the selected sources and say if they do not cover this" keeps it honest.