ChatGPT and Google's AI Overviews Share Only 8.4% of the Websites They Cite

    When ChatGPT and Google AI Overviews answer the same question, only 8.4% of the websites they cite are the same. Across five AI engines, any two share 15.4% of their sources on average, so being cited by one engine says little about the others.

    Websites in common by engine pair
    Google AI Mode and Google AI Overviews
    37.8%
    Gemini and Google AI Overviews
    18.2%
    Gemini and Google AI Mode
    17.3%
    Google AI Overviews and Perplexity
    16.8%
    Google AI Mode and Perplexity
    16.4%
    ChatGPT and Google AI Mode
    10.6%
    Gemini and Perplexity
    10.5%
    ChatGPT and Gemini
    8.6%
    ChatGPT and Google AI Overviews
    8.4%
    ChatGPT and Perplexity
    8.2%
    All 10 pairs
    15.4%

    Source: Suff Digital analysis of 27,665 paired AI answers to 2,984 questions · answers from ChatGPT, Gemini, Perplexity and Google's AI features, September 2026

    Questions by website cited by all five engines
    irs.gov
    14
    apple.com
    11
    microsoft.com
    9
    wikipedia.org
    6
    nih.gov
    4
    progressive.com
    4
    aboutamazon.com
    4
    bia.gov
    3
    petmd.com
    3
    delta.com
    3

    Source: Suff Digital analysis of 27,665 paired AI answers to 2,984 questions · answers from ChatGPT, Gemini, Perplexity and Google's AI features, September 2026

    Source: ChatGPT and Google's AI Overviews Share Only 8.4% of the Websites They Cite - Suff Digital