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GPT-5.1: New GPT-5 Model with More Adaptive Reasoning & Conversational Tone

GPT-5.1 is OpenAI’s latest update to the GPT-5 family, announced in November 2025. It introduces two primary operating modes, Instant and Thinking, designed to balance speed and deep reasoning, along with improved tone control and better alignment for more natural, reliable conversations.

GPT-5.1 Instant prioritizes low latency for quick, transactional tasks, while Thinking mode allocates more reasoning resources for complex prompts, enabling deeper analysis and more thorough multi-step solutions.

The update also emphasizes adaptive reasoning, personalized tone options, and stronger instruction adherence, making GPT-5.1 better suited for both casual use and enterprise automation. Overall, GPT-5.1 aims to deliver faster responses without sacrificing accuracy, with a more conversational, warmer user experience by default.

Core Features and Improvements of GPT-5.1

GPT-5.1 comes with the following features and improvements:

• Adaptive Reasoning: GPT-5.1 dynamically adjusts "thinking time" based on query complexity—faster for simple tasks (up to 2x quicker than GPT-5) and more deliberate for challenging ones (up to 2x slower but more accurate). This reduces overthinking on easy prompts and boosts thoroughness on hard ones, like math, coding, or planning.
• Enhanced Conversation and Personality: Described as "warmer" and more natural, it includes eight customizable personality presets (e.g., professional, concise, or empathetic) to tailor response tone. It follows instructions more precisely, uses less jargon, and hallucinates fewer facts.
• Variants:
  • GPT-5.1 Instant (default for most ChatGPT tasks): Optimized for speed and casual chat, with better instruction adherence.
  • GPT-5.1 Thinking: For complex problem-solving, like graduate-level science or agentic coding, with improved benchmarks (e.g., 76.3% on SWE-bench for coding).

Key Benchmark Performance of GPT-5.1

Benchmark	Description	GPT-5.1 Score	Notes
SWE-bench Verified	Coding: Resolves real-world GitHub issues (enterprise-style, multi-file)	76.3%	Tops Claude Sonnet 4.5 (77.2% in some evals, but GPT-5.1 leads in precision/recall per CodeRabbit).
GPQA Diamond (no tools)	Reasoning: PhD-level questions in biology/physics/chemistry	88.1%	Strong gains in expert knowledge.
MMMU	Multimodal: Multi-discipline understanding (vision + text)	85.4%	Incremental multimodal boost.
FrontierMath	Advanced math: Frontier-level problems	26.7%	Minimal change; persistent on hard tasks.

How GPT-5.1 Compares to GPT-5 and Claude Sonnet 4.5

GPT-5.1 edges out GPT-5 in everyday tasks but trails Claude Sonnet 4.5 in coding reliability and creative depth. Claude excels in long-context agent workflows, while GPT-5.1 prioritizes personalization and speed.

Aspect	GPT-5.1	GPT-5	Claude Sonnet 4.5
Release Date	November 12, 2025	August 2025	September 29, 2025
Core Strengths	Adaptive reasoning; warmer, more empathetic tone; better instruction following.	Strong multi-step reasoning; multimodal integration; broad tool use.	Agentic workflows; reduced hallucinations; political neutrality (95% even-handedness score).
Context Window	Up to 400K tokens (272K input + 128K output)	Up to 400K tokens	~200K tokens, with memory features for session continuity
Coding Performance	76.3% on SWE-bench Verified	70-72% on SWE-bench	77.2% on SWE-bench
Creative Tasks	Clever, high-concept ideas (e.g., plot twists with AI tropes)	Balanced but sometimes robotic	Wins in psychological depth and subversion; more imaginative and culturally savvy.
Reasoning & Accuracy	Dynamic reflection passes for coherence; 2x faster on simple tasks, 2x slower on complex; fewer jargon-heavy responses.	Variable performance; requires "Thinking" mode for peaks.	Steady accuracy without mode-switching; strong in math/logic (near specialist levels) and abstract reasoning.
Pricing (API)	$1.25/M input tokens, $10/M output (cheaper than GPT-5 base); caching discounts.	$2.50/M input, $15/M output.	Same as predecessor (~$3/M input, $15/M output); competitive with batching.

Availability of GPT-5.1

Here is the most reliable ways for you to get access to GPT-5.1:

• OpenAI started rolling out GPT-5.1 to ChatGPT paid users (Plus, Pro, Team, Enterprise) first, then free users.
• API access started November 13, 2025. GPT-5.1 is available in the OpenAI API as gpt-5.1-instant and gpt-5.1-thinking, with unchanged pricing from GPT-5. There are also new additions include gpt-5.1-codex for long coding sessions and 24-hour prompt caching.
• You can also access GPT-5.1 on HIX AI! As an all-in-one AI agent platform, you can chat with all the latest language models easily and smoothly, including GPT-5.1, GPT-5, Claude Sonnet 4.5, Claude Haiku 4.5, Gemini 2.5 Pro, and a lot more.