OpenAI Launches GPT-5.5 Instant

OpenAI rolled out GPT-5.5 Instant, the new default ChatGPT model, to all users on 5 May 2026.
GPT-5.5 Instant cuts hallucinated claims by 52.5% versus GPT-5.3 and reduces factual errors by 37.3% on flagged conversations.
Benchmark scores improve, with AIME math accuracy up to 81.2% (from 65.4%), GPQA 85.6% (from 78.5%) and CharXiv visual reasoning 81.6% (from 75.0%).
New “memory sources” feature lets users view, delete, or correct past chat context and integrates Gmail data for personalized answers.