If your main use for an AI assistant is research, meaning reading sources, synthesizing them and citing them, the choice between ChatGPT and Gemini comes down to less obvious details. The headline feature is now the same on both: a "deep research" mode that drafts a plan, browses the web and returns a report with citations. The differences that matter are how much text each plan can hold at once, how each reads PDFs, which of your own sources it can search, what it costs to get a large context window, and what happens to your data.
This comparison uses only the companies' current pricing, help and privacy pages, plus two clearly labeled independent studies.
Last verified: October 8, 2026
The short answer
- For long documents and large source sets on a mainstream budget, Gemini is better. A $19.99 Google AI Pro plan includes a 1M-token context window. Gemini Notebook (the product formerly called NotebookLM) allows up to 300 sources per notebook on that plan.
- For controlled, exportable web research, ChatGPT is better. Its deep research can be limited to specific websites or told to prefer them, connects read-only to apps such as Google Drive and SharePoint, and exports reports to Markdown, Word or PDF.
- If your work already lives in Gmail and Google Drive, choose Gemini. Deep Research can search them directly.
- If you need the most privacy without a business plan, it's close. Both let you turn off model training, but the settings work differently. Details below.
Deep research, side by side
| ChatGPT deep research | Gemini Deep Research |
|---|
| Plan before it runs | Yes, editable; you can interrupt mid-run | Yes, editable ("Edit plan") |
| Default sources | Public web and your uploaded files | Google Search |
| Other sources | Connected apps such as Google Drive and SharePoint (read-only, plan-dependent) | Gmail and Drive (requires connecting Workspace), uploaded files, notebooks |
| Restrict to specific sites | Yes (Sites > Manage sites: restrict or prioritize domains) | Not described in Google's help page; you can only deselect Google Search |
| Citations | "Every output includes citations or source links" | Cited report (format not specified in help page) |
| Output | Full-screen report with table of contents and a sources-used section | Report in Canvas; can generate an Audio Overview or a custom visualization |
| Export | Markdown, Word, PDF | Google Docs, share link, copy |
| Typical duration | "Longer than standard search" (no figure) | Usually 5–10 minutes |
| Extras | — | AI Ultra reports can include charts, diagrams and interactive simulators (not when Workspace sources are included) |
| Published quotas | None. Fixed allowances reset 30 days after first use | None. Daily and concurrent-run limits apply |
| Free plan | "Limited" | Included |
Sources: OpenAI's "Deep research in ChatGPT" help article and pricing page; Google's "Use Deep Research in Gemini Apps" help page and plans page. Last verified: October 8, 2026
In practice, ChatGPT's site controls are the bigger difference. If you only trust certain sources, such as a regulator's website, a set of journals or your company's documentation, you can limit deep research to those domains. Gemini starts from Google Search by default, which gives broad coverage but less control.
A practical gap on the Gemini side: Google's new skills feature, which replaces Gems, doesn't work with Deep Research yet. If you relied on a Gem to steer report style, see our report on Gemini skills.
How much each plan can read at once
The context window is how much text the model can hold in a single conversation. For research, it limits how much of a long report, contract or book the assistant can see at the same time.
| Plan | Price (US, per month) | Context window | Notes |
|---|
| ChatGPT Free | $0 | 27K (GPT Instant) | Reasoning context "varies" |
| ChatGPT Go | $8 | 54K Instant / 256K reasoning | OpenAI says about 40 / 320 pages; may include ads |
| ChatGPT Plus | $20 | 54K Instant / 256K reasoning | About 40 / 320 pages |
| ChatGPT Pro | $100, $200 or $500 | 128K Instant / 400K reasoning | About 250 / 680 pages; tiers differ by included usage |
| Gemini, no plan | $0 | 32K | |
| Google AI Plus | $4.99 | 128K | 2x standard usage |
| Google AI Pro | $19.99 | 1M | Google says up to 1,500 pages; 4x standard usage |
| Google AI Ultra | From $99.99 ($199.99 tier) | 1M (Deep Think: 192K) | 5x or 20x Pro usage |
Sources: chatgpt.com/pricing, OpenAI help center (Plus, Pro tiers), OpenAI's ChatGPT Go announcement, gemini.google/subscriptions, Gemini Apps limits help page. Last verified: October 8, 2026. Prices are US list prices before tax. ChatGPT Go pricing is "localized in some markets," and ChatGPT Business prices vary by country and currency. Check your local pricing page.
The gap is large. At about $20 a month, Gemini gives you four times the largest context window ChatGPT Plus offers. ChatGPT's largest window, 400K tokens, requires a Pro plan starting at $100. A bigger window doesn't guarantee better recall of details deep inside a long document. Our explainer on context windows vs memory vs retrieval covers why.
Files and PDFs
| ChatGPT | Gemini app |
|---|
| Max size per file | 512 MB (spreadsheets about 50 MB; images 20 MB) | 100 MB (video 2 GB) |
| Text cap per document | 2M tokens per file | Bounded by plan context window |
| Upload rate | Up to 80 files per 3 hours; Free: 3 uploads per day | Up to 10 files per prompt |
| Images inside PDFs | Text-only retrieval on all plans except Enterprise (embedded images discarded) | Not specified on the help page |
| Persistent source collections | Projects: 5 (Free), 25 (Go, Plus), 40 (Pro, Business, Enterprise, Edu) files | Gemini Notebook: 50 (Free), 100 (Plus), 300 (Pro), 500 or 600 (the two Ultra storage tiers) sources per notebook |
Sources: OpenAI file uploads FAQ; Gemini Apps upload help; Gemini Notebook plans and sources help. Last verified: October 8, 2026
One point matters for anyone working with reports, papers or slide decks. OpenAI's help center says that outside ChatGPT Enterprise, PDFs get "text-based retrieval," and embedded images such as charts and scanned figures are discarded. If your sources depend on charts, that is a real limitation.
Gemini Notebook has the largest published source capacity of either side's tools for working within a fixed set of sources. Google renamed NotebookLM to Gemini Notebook on July 16, 2026. It is still a standalone product at notebooklm.google and now syncs with the Gemini app. Each source can be up to 500,000 words or 200 MB, and Google says files added as notebook sources are "not used directly for training." ChatGPT's closest equivalent, Projects, holds at most 40 files. Our explainer on how Gemini handles very large PDFs covers the exact limits for a single huge document.
Usage limits
Neither company publishes exact numbers for deep research.
- ChatGPT: OpenAI's help center (checked October 8, 2026) says Free and Go include "unlimited everyday text chats" subject to abuse safeguards, with separate limits for uploads and data analysis. Plus gets "expanded" deep research, and Pro the "maximum." The in-product counter shows how many tasks you have left.
- Gemini: Usage refreshes every five hours until you hit a weekly limit. Plans are sold as multiples: Plus is 2x the free allowance, Pro 4x, and Ultra 5x or 20x Pro. Deep Research and higher thinking levels "consume more of your usage." Subscribers who hit their limit can keep going on a lighter Flash-Lite model.
Privacy and data use
| ChatGPT (Free, Go, Plus, Pro) | Gemini (personal accounts) |
|---|
| Training on your chats | Yes, unless you turn off Improve the model for everyone (Settings > Data controls) | Yes while Keep Activity is on |
| How to opt out | Toggle off; your chat history stays | Turn off Keep Activity; future chats aren't used for training |
| Private/temporary mode | Temporary Chat: not used for training, kept up to 30 days | Temporary chats: not used for training, kept 72 hours |
| Human review | Not covered on the data-controls page | A subset of chats is reviewed; reviewed chats are kept up to 3 years, disconnected from your account |
| Default retention | Until you delete; removed within 30 days of deletion | Auto-delete after 18 months (options: 3 or 36 months, or off) |
| Business plans | Business, Enterprise and Edu: not used for training by default | Workspace terms apply (separate privacy hub) |
Sources: OpenAI "Data controls in ChatGPT" and file uploads FAQ; Google Gemini Apps Privacy Hub. Last verified: October 8, 2026
There's a catch for Gemini users: some newer features require Keep Activity to be on. Skills are one example, and saved past Deep Research reports are another. Turning off training also turns those off. In ChatGPT you can keep your history while opting out of training. One caveat on the ChatGPT side: if you rate a response with a thumbs up or down after opting out, OpenAI says the whole conversation may still be used for training.
What independent evaluations say
There is no recent independent head-to-head comparison of the two consumer deep research products. The two most relevant studies:
- DeepResearch Bench (University of Science and Technology of China and Metastone Technology; paper arXiv 2506.11763, first posted June 2025) scores report quality on 100 PhD-level tasks with an LLM judge (its RACE framework, which used Gemini 2.5 Pro as the judge model) and citation accuracy with its FACT framework. In its published table, Gemini-2.5-Pro Deep Research scored 48.88 overall against 46.98 for OpenAI Deep Research. Citation accuracy was 81.44% vs 77.96%, and Gemini produced far more "effective citations" (111.21 vs 40.79). These results cover older product versions and may not reflect today's models.
- "Cited but Not Verified" (PwC researchers, arXiv preprint, May 7, 2026; not peer-reviewed) tested models running as research agents with a custom prompt. These were not the consumer apps. Links almost always worked (94–100%), but whether the cited page actually supported the claim was much weaker: 39–59% for OpenAI models and 45–49% for Google models. On one OpenAI model, accuracy fell from 78.6% to 16.7% as the agent made more tool calls.
The takeaway applies to both: a citation is a pointer, not proof. Check every cited source for any claim you intend to publish or rely on.
Recommendation by use case
| If you mainly… | Pick | Why |
|---|
| Read very long PDFs, books or filings | Gemini (AI Pro) | 1M-token context for $19.99; ChatGPT needs Pro ($100+) for 400K |
| Work from a fixed library of sources | Gemini Notebook | Up to 300 sources per notebook on AI Pro, each up to 500k words |
| Need web research limited to trusted domains | ChatGPT | Sites can be restricted or prioritized in deep research |
| Need Word/PDF exports for clients | ChatGPT | Markdown, Word and PDF export built in |
| Research across your Gmail and Drive | Gemini | Deep Research searches them directly |
| Rely on charts and figures inside PDFs | Gemini, or ChatGPT Enterprise | Other ChatGPT plans discard images embedded in PDFs |
| Want a low-cost entry with some long context | Google AI Plus ($4.99, 128K) | Cheapest plan with a context window above 100K |
| Want an assistant that can act on web pages, not just read them | ChatGPT, through ChatGPT Work and its cloud browser (agent mode itself has been retired; Gemini's equivalents are outside this comparison) | See our ChatGPT agent mode explainer |
Model lineups change quickly. Google's newest frontier model, Gemini 4 Argon, isn't in the Gemini app yet; our Argon report has the rollout details. A full side-by-side summary is also on our ChatGPT vs Gemini compare page.