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ChatGPT conducts much of its background research in English regardless of the user’s language. Peec analyzed over 10 million prompts and 20 million query fan-outs, filtered to cases where user location matched query language — Polish queries from Poland, German from Germany, Spanish from Spain (full study, Feb 2026).
  • In nearly 78% of non-English cases, ChatGPT supplements the query with additional English-language research; across all non-English sessions analyzed, at least one sub-search hits the English web.
  • 43% of all fan-out research steps for non-English prompts run in English.
  • By language: Turkish switches most at 94%, Spanish least at 66% — no non-English language falls below 60% (Feb 2026 data).
The consequence: local market leaders lose to global brands in their home market. Documented examples include German software queries returning zero German companies, and Allegro.pl (Poland’s dominant marketplace) missing from Polish auction-portal answers while eBay ranks. ChatGPT even rewrote a Spanish cosmetics query into “top global cosmetic brands” on its own. Why: English content carries more authority signals (backlinks, citations), and with ~50% of internet content in English, English queries reduce retrieval risk. What to do: identify which English sources ChatGPT trusts in your category and get present in them — strategic English content beats blind translation. Google’s surfaces stay closer to the query language — see Optimizing for Google AI vs ChatGPT and Translated Reddit citations. Source: ChatGPT searches in English, even when you don’t, Peec (Tomek Rudzki), Feb 2026.