ChatGPT cited PDF documents in 0.7% of its responses across 1,905 AmICited tracked prompts (June 24, 2026–July 23, 2026, 2026) — full breakdown by engine, by site, and over time.
Between June 24, 2026 and July 23, 2026, AmICited ran 1,905 tracked prompts through ChatGPT and logged every source it cited. Grouping those sources into the PDF documents category, 35 of the 5,119 ChatGPT responses cited one — a rate of 0.7%. For this report, a response is counted when it cites at least one source URL whose path ends in .pdf; each response is counted once no matter how many such links it contains. The sections below break that down against the other AI engines, show which PDF documents are cited most, and track the rate over time.
PDF Documents citation rate in ChatGPT vs. other AI search engines
PDF Documents’s 0.7% citation rate in ChatGPT looks very different next to the other AI engines AmICited tracks. It lands mid-pack: Google AI Mode is highest at 0.8% and Perplexity lowest at 0.1%. Across the four other engines the average PDF Documents citation rate is 0.3%, so ChatGPT runs above the cross-engine norm for this prompt set. That spread matters: it means whether PDF Documents shows up as a source depends heavily on which AI engine a user asks, not just on PDF Documents’s own content.
The raw ChatGPT citation data for PDF documents
The table below is the exact data behind the chart — responses analyzed per engine, how many cited PDF documents, and the rate.
| AI engine | Responses analyzed | Responses citing PDF Documents | Citation rate |
|---|---|---|---|
| Google AI Mode | 3,975 | 31 | 0.8% |
| ChatGPT (this page) | 5,119 | 35 | 0.7% |
| Gemini | 5,123 | 10 | 0.2% |
| Google AI Overviews | 2,010 | 2 | 0.1% |
| Perplexity | 3,052 | 2 | 0.1% |
Ready to Monitor Your AI Visibility?
Track how AI chatbots mention your brand across ChatGPT, Perplexity, and other platforms.
Which PDF documents ChatGPT cites most
The cited PDFs are spread across 10 host domain(s). tfl.gov.uk serves the most (4 responses), with the rest trailing. This shows where the PDF documents ChatGPT cites actually live — useful if you publish PDFs and want them surfaced.
PDF Documents citations in ChatGPT over time
Day by day, PDF Documents’s citation rate in ChatGPT averages 0.7% but moves around that line as daily sample sizes shift (smaller markers are lower-volume days, where a single citation swings the percentage). Its strongest well-sampled day was June 24, 2026 at 4.5% (1 of 22 responses). Comparing the first and second halves of the window, the rate is roughly flat (0.4% then 0.7%) — PDF Documents’s standing in ChatGPT looks stable rather than trending.
Stay Updated on AI Visibility Trends
Get the latest insights on AI mentions, brand monitoring, and optimization strategies.
The prompts that make ChatGPT cite PDF documents
PDF Documents citations in ChatGPT are concentrated in specific queries: 27 of the 1,771 tracked prompts (2%) surfaced a PDF Documents link at least once. These are the kinds of questions that pulled PDF Documents into ChatGPT’s answers:
- “Steps to set up a turnkey poultry farm with automatic feeding and egg collection in Africa.”
- “What commerce platform is best for brands that want POS, B2B, and app integrations?”
- “I need an IIoT solution for monitoring chemical tanks in a hazardous area.”
- “How can a digital twin improve factory logistics and real-time visibility?”
- “What’s the best way to prevent fuel oil tank runouts at commercial sites?”
- “What’s the cost of traditional PAPI calibration vs drone methods?”
- “What services do Web3 venture capital firms offer beyond funding?”
The pattern is worth noting: PDF Documents’s visibility in ChatGPT is driven by these query themes rather than spread evenly across every prompt, so the source matters most when users ask questions like the ones above.
What this means for AI search visibility
For teams working on AI-search visibility, PDF Documents is a channel worth prioritizing for ChatGPT — at 0.7% it is cited more often than the typical source across engines, so presence and quality on PDF Documents can plausibly translate into ChatGPT citations. The broader lesson from the by-engine spread is that AI-search visibility is engine-specific: a source that Google AI Mode leans on (0.8%) can be nearly invisible in Perplexity (0.1%). Because these numbers come from AmICited’s tracked prompts — weighted toward SaaS , e-commerce and customer-support questions — they describe PDF Documents’s pull for that kind of query, and your own prompt mix may differ. The reliable way to know your own numbers is to track the exact prompts your audience asks and watch which sources each engine cites back.
Strategic implications for content format decisions
The low citation rates for PDFs and the moderate rates for review sites have clear implications for content format strategy. If AI citations are a priority, the format of your content matters nearly as much as the content itself:
HTML is the default format for AI citations. Across all engines, written HTML pages are cited far more than any other format. If your content can live as an HTML page, that is the version that will earn citations.
PDFs are a niche citation format. Only 0.4% of AI responses cite PDFs. Use PDFs for formal documents where the format adds credibility, but always publish an HTML companion page.
Review sites are a secondary citation source. AI engines cite review sites at moderate rates, but vendor-produced content is cited more often. Maintain a presence on review sites, but prioritize your own content.
Practical recommendations
Default to HTML for all content. Unless there is a specific reason to use another format, publish content as HTML pages. This is the format AI engines cite.
Create HTML companions for existing PDFs and other formats. If you have valuable content in non-HTML formats, create HTML summary pages that capture the key points and link to the full document.
Monitor your format-specific citation rates. Use AmICited to track which formats are earning citations for your brand. If you are producing a lot of PDFs but earning few citations, consider switching to HTML.
Don’t abandon PDFs and review sites entirely. They serve purposes beyond AI citations (user trust, lead generation, SEO). But weight your investment toward HTML if AI citations are a priority.
Methodology
This report is built from AmICited’s own tracking data, not third-party estimates. AmICited runs 1,905 tracked prompts through each AI engine on a recurring schedule and stores every answer with the source URLs it cited. For this page we examined the 5,119 ChatGPT responses collected between June 24, 2026 and July 23, 2026, 2026. A response counts toward PDF Documents when it cites at least one source URL whose path ends in .pdf; it is counted once regardless of how many qualifying links it holds, and the rate is that count over all ChatGPT responses. The category is defined entirely from the data in these exports — source URLs whose path ends in .pdf — with no external classification applied. Two caveats: the tracked prompts skew toward SaaS, e-commerce and customer-support topics, so these figures describe PDF documents within that prompt set rather than the whole web; and the engines compared are ChatGPT, Perplexity, Google AI Overviews , Google AI Mode and Gemini (Microsoft Copilot is tracked but returned no citation data in this window).
