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OpenAI: GPT-5.1-Codex-mini

openai/gpt-5.1-codex-mini

GPT-5.1-Codex-mini is OpenAI’s proprietary AI model, released Nov 12, 2025. It costs $0.25/M input and $2/M output tokens, and handles a 400K-token context window.

GPT-5.1-Codex-Mini is a smaller and faster version of GPT-5.1-Codex

Context
400K
Input
$0.25 / 1M
Output
$2 / 1M
Released
Nov 12, 2025
Modalities
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Benchmarks

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

43.0
Intelligence Index
Epoch AI
43rd percentile of tracked models
46.0
Coding Index
Epoch AI
46th percentile of tracked models
42.0
Agentic Index
Epoch AI
42nd percentile of tracked models

Reasoning

3 evals
GPQA Diamond81.3%

Graduate-level scientific reasoning

Humanity's Last Exam18.5%

Frontier of human expert knowledge

MMLU-Pro82.0%

Broad expert knowledge

Coding

3 evals
LiveCodeBench83.6%

Contamination-free coding

SciCode42.6%

Scientific research coding

WebDev Arena1247

Human-rated web development

Math

1 evals
AIME 2024/202591.7%

Olympiad-qualifier math

Agentic & Tools

2 evals
Terminal-Bench61.6%

Command-line agentic tasks

τ²-bench62.9%

Tool-agent-user reliability

Changelog

1
  • GPT-5.1-Codex-mini: Humanity's Last Exam improved from 16.9% to 18.5% (+9%)benchmark · Aug 6, 2026

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Frequently asked questions

What is GPT-5.1-Codex-mini?

GPT-5.1-Codex-Mini is a smaller and faster version of GPT-5.1-Codex

Who created GPT-5.1-Codex-mini?

GPT-5.1-Codex-mini is an AI model developed by OpenAI, part of the GPT family, released Nov 12, 2025.

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

GPT-5.1-Codex-mini is served from $0.25 per million input tokens and $2 per million output tokens (cheapest credible provider on OpenRouter: OpenAI).

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

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

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

On standardized evaluations tracked by Epoch AI, GPT-5.1-Codex-mini scores 83.6% on LiveCodeBench, 61.6% on Terminal-Bench, 91.7% on AIME 2024/2025.

Is GPT-5.1-Codex-mini open source?

GPT-5.1-Codex-mini 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 Sep 17, 2026.