Factual Density
Factual density is how many facts a piece of writing holds for its length. Researchers led by Elisabeth Lex suggested it in 2012 as a way to measure how informative a web page is: count the facts, then divide by the length. Here a fact is a simple statement software can pull from a sentence, like who did what.
Source: Horn, Zhila, Gelbukh, Kern and Lex, Using Factual Density to Measure Informativeness of Web Documents (NODALIDA 2013), checked October 29, 2026
What Factual Density means for your business
A 2013 study by Christopher Horn and colleagues counted facts with software and found the scores partly matched how people ranked the same pages. SEO writers have since borrowed the phrase for how many specific, checkable facts a page gives AI tools to quote. You'll also see it called claim density.
The closest test on AI answers is a 2023 study by Pranjal Aggarwal and colleagues. In their setup, adding statistics, quotes from credible sources and citations made pages show up more in AI-written answers, and adding more keywords did little. That was their test. We haven't seen ChatGPT or Google say they pick sources that way.
On a business page, we'd look for sentences that say nothing a buyer could check, like praise for your quality and care. We'd swap them for facts: what you do and don't do, where you work, who does the job and what it involves. We'd never pad a page with numbers you can't back up.
If your pages sound good but never say what you do, where or for whom, rewriting them around facts a buyer can check is how we'd fix it.
Last reviewed October 29, 2026. All terms
How AI answers it today
On October 29, 2026, Google's AI Overview cited the 2012 and 2013 research papers alongside GEO tool sites and our own old wiki entry. ChatGPT offered a facts-per-word formula, said no standard one exists, and cited nothing.
Our run through ChatGPT and Google's AI Overview, October 29, 2026. A sample, not what every buyer sees.
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