What are the strengths of this model?

Equipped with advanced reasoning Long 400K context retention Latest design from OpenAI

What are the weaknesses of this model?

License is not public Source code not disclosed Closed usage environment

What are the best use cases?

Complex logical reasoning tasks Analyzing lengthy documents Automating advanced problem-solving

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OpenAIProprietary

GPT-5.1 Pro

Name: GPT-5.1 Pro
Author: OpenAI

GPT-5.1 Pro is a foundation model developed by OpenAI. It is positioned as a reasoning model and features an extensive context window of 400K.

Parameters

Undisclosed

Context Window

400K

License

Proprietary

Release Date

2025-11-20

API Pricing

API pricing for this model is not yet available

Strengths

・Equipped with advanced reasoning
・Long 400K context retention
・Latest design from OpenAI

Weaknesses

・License is not public
・Source code not disclosed
・Closed usage environment

Use Cases

・Complex logical reasoning tasks
・Analyzing lengthy documents
・Automating advanced problem-solving

Deep Analysis

Release Date

November 12, 2025

Context Window

410K tokens

Max Output

128K tokens

Input Price

$1.25 / 1M tokens

Output Price

$10.00 / 1M tokens

Modality

Multimodal (Text, Image, File input)

Architecture

Reasoning (chain-of-thought)

Knowledge Cutoff

September 2024

Strengths

・Designed for logic-heavy and multi-step tasks with strong reasoning capabilities
・Large 410K context window with 128K max output for comprehensive analysis
・Cost-effective reasoning model at $1.25/$10 per 1M tokens
・Supports configurable reasoning effort levels (medium, high)
・Strong foundation for the GPT-5.1 Codex family of coding models

Weaknesses

・Superseded by GPT-5.2 which offers 30% fewer errors at the same price
・Slower than GPT-5.1 Instant for interactive use cases
・Knowledge cutoff of September 2024 is older than GPT-5.2's August 2025
・Weaker agentic and tool-use capabilities compared to GPT-5.2
・No longer the recommended model — OpenAI suggests GPT-5.2 as the upgrade

Competitor Comparison

Model	Arena	SWE	GPQA	Price
Claude Sonnet 4.5	~1420	~72%	~89%	$3/$15 per 1M tokens
Gemini 3 Pro	~1420	76.2%	~90%	$3.50/$10.50 per 1M tokens
GPT-5.2 Thinking	1436	80.0%	92.4%	$1.75/$14 per 1M tokens
GPT-5	~1390	~68%	~85%	$1.25/$10 per 1M tokens

Overview

GPT-5.1 (Thinking/Pro mode) is OpenAI's reasoning-focused model released November 12, 2025, designed for logic-heavy and multi-step tasks. With a 410K context window and configurable reasoning effort, it offered significant improvements over GPT-5 for complex analytical work. It has since been superseded by GPT-5.2, which provides 30% fewer errors at a similar price point.

Benchmarks & Performance

GPT-5.1 represents a significant step up from GPT-5 in reasoning capability with its chain-of-thought architecture. Specific benchmark scores for the Thinking variant are not individually published, but the GPT-5.1 family is designed for logic-heavy multi-step tasks. GPT-5.1 Codex (built on the same foundation) achieves SWE-bench Verified 73.7% and Terminal-Bench 2.0 52.8%. The model supports multiple reasoning effort levels for cost/quality tradeoffs.

Detailed Comparison

GPT-5.1 Thinking has been largely superseded by GPT-5.2 Thinking, which offers 30% fewer response errors at a slightly higher price ($1.75/$14 vs $1.25/$10). Compared to Claude Sonnet 4.5 ($3/$15), it is significantly cheaper but may trail on some coding benchmarks. It offers better value than Gemini 3 Pro ($3.50/$10.50) for reasoning tasks. OpenAI recommends upgrading to GPT-5.2 for new projects.

Community Feedback

GPT-5.1 was well-received upon release as a major improvement over GPT-5 for analytical tasks. Developers appreciated the configurable reasoning effort levels. However, with GPT-5.2's release just one month later, the community quickly migrated to the newer model. GPT-5.1 remains in use for cost-sensitive workloads where the 30% error reduction of GPT-5.2 doesn't justify the 40% price increase.

Use Cases

Suitable for: multi-step logical reasoning, code debugging and refactoring, mathematical problem solving, data consistency checks, document analysis, and structured proposal generation. Also works for: spreadsheet and presentation generation, strategic analysis, and research synthesis. For new projects, GPT-5.2 Thinking is recommended as the superior successor. GPT-5.1 is best retained for existing integrations where cost optimization is critical.

Latest News

Released November 12, 2025. The GPT-5.1 Instant and Thinking System Card Addendum was published by OpenAI. GPT-5.2 was released just one month later (December 11, 2025) as the recommended upgrade. OpenAI's Artificial Analysis page now suggests 'considering GPT-5.2 (xhigh) instead'.

Sources

Analysis generated: 2026-05-24