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Models/GPT-5.1-Codex-Max
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OpenAI: GPT-5.1-Codex-Max

openai/gpt-5.1-codex-max

GPT-5.1-Codex-Max is OpenAI’s proprietary AI model, released Nov 19, 2025. It costs $1.25/M input and $10/M output tokens, and handles a 400K-token context window. Its strongest use case is coding, where it ranks in the 70th percentile of the models Model Beat tracks.

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks.

Context
400K
Input
$1.25 / 1M
Output
$10 / 1M
Released
Nov 19, 2025
Modalities
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Strongest atCoding top 30%

Benchmarks

Scores on standardized evaluations. Higher is better — and rank shows where GPT-5.1-Codex-Max lands among all models tracked on Model Beat.

61.0
Intelligence Index
Epoch AI
61st percentile of tracked models
70.0
Coding Index
Epoch AI
70th percentile of tracked models
51.0
Agentic Index
Epoch AI
51st percentile of tracked models

Agentic & Tools

2 evals
METR task horizon2.7 h

Autonomous task length

Terminal-Bench60.4%

Command-line agentic tasks

In the news

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Frequently asked questions

What is GPT-5.1-Codex-Max?

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks.

Who created GPT-5.1-Codex-Max?

GPT-5.1-Codex-Max is an AI model developed by OpenAI, part of the GPT family, released Nov 19, 2025.

How much does GPT-5.1-Codex-Max cost?

GPT-5.1-Codex-Max's list price from OpenAI is $1.25 per million input tokens and $10 per million output tokens.

What is GPT-5.1-Codex-Max's context window?

GPT-5.1-Codex-Max supports a context window of up to 400K tokens.

How does GPT-5.1-Codex-Max perform on benchmarks?

On standardized evaluations tracked by Epoch AI, GPT-5.1-Codex-Max scores 60.4% on Terminal-Bench, 2.7 h on METR task horizon.

Is GPT-5.1-Codex-Max open source?

GPT-5.1-Codex-Max is a proprietary model (API access), available through its provider's API rather than as a downloadable open-weight model.

Benchmark data from Epoch AI (CC BY) and Artificial Analysis; pricing, specs & descriptions from OpenRouter. Data updated Jul 30, 2026.