OpenAI has rolled out GPT-5.1, the latest upgrade in its GPT-5 series, bringing two new models—GPT-5.1 Instant and GPT-5.1 Thinking—designed to deliver more intelligent, natural, and customizable chatbot interactions. The update directly responds to user feedback from the GPT-5 launch, where automatic model selection removed the ability to personalize the ChatGPT experience. With GPT-5.1, OpenAI aims to restore that control while improving performance across reasoning, coding, and conversational quality.
GPT-5.1 Instant optimizes for everyday queries, offering a warmer tone, better instruction-following, and improved conversational flow. It also introduces adaptive reasoning, allowing the model to “think” longer when faced with complex prompts and stay fast on simpler tasks. Early benchmarks show strong gains on mathematical (AIME 2025) and coding (Codeforces) evaluations.
GPT-5.1 Thinking targets more sophisticated workloads, adjusting its reasoning time dynamically based on prompt difficulty. OpenAI’s internal testing shows it now calibrates thinking speed more efficiently, generating clearer and less jargon-heavy answers for technical or multistep questions.
Both models are rolling out first to paid ChatGPT tiers—Pro, Plus, Go, and Business—and will later become available to free users. GPT-5 Auto remains the default automatic selector, while GPT-5 Pro will soon be upgraded to GPT-5.1. Legacy GPT-5 models will remain accessible for a three-month comparison period.
A major part of the update focuses on personalization. Users can now choose from expanded personality modes—including Professional, Candid, and Quirky—and fine-tune factors like warmth, conciseness, and scannability. ChatGPT can also adjust response style automatically based on conversation cues. Custom instructions have been improved to apply instantly across all ongoing chats, further enhancing continuity and control.
The new features underscore OpenAI’s push to make ChatGPT not only more capable, but also more human-aligned, flexible, and user-tailored as AI adoption accelerates.
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