GPT-5.1 Codex Mini
GPT-5.1 Codex Mini is OpenAI's smaller, faster version of GPT-5.1 Codex, callable only via the Responses API for agentic coding in Codex harnesses.
Model Overview
Capabilities, design details, and architectural traits
GPT-5.1 Codex Mini - The Smaller, Faster Version of GPT-5.1 Codex
GPT-5.1 Codex Mini is documented as a smaller, faster version of GPT-5.1 Codex, OpenAI's coding-focused variant of GPT-5.1. It carries the same purpose as its larger sibling, agentic coding inside Codex or Codex-like harnesses, but in a lighter form.
| Trait | Detail |
|---|---|
| Defining purpose | A smaller, faster version of GPT-5.1 Codex, built for agentic coding tasks in Codex or Codex-like harnesses rather than general-purpose use. |
| Deployment model | Callable only through the Responses API, the same access restriction OpenAI documents for its other Codex-tuned models. |
| Release pairing | Released together with GPT-5.1 and GPT-5.1 Codex as the lighter option in that same model set. |
A Lighter Tier in the Codex Lineup
OpenAI's developer announcement groups gpt-5.1-codex and gpt-5.1-codex-mini together as the same family of models optimized for long-running, agentic coding work. The Mini variant exists specifically to offer that same agentic-coding tuning in a smaller, faster form rather than as a separate use case.
Benchmark Performance
Independent evaluations · Artificial Analysis
Accuracy & Capability Details
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| Model Details | |||
|---|---|---|---|
| General Info | |||
| Provider | OpenAI | Anthropic | Anthropic |
| Release Date | November 13, 2025 | September 22, 2026 | September 28, 2026 |
| Knowledge Cutoff | Sep 2024 | - | Jun 2026 |
| Context & Limits | |||
| Context Window | 400K | 1M Best Context Window | 1M Best Context Window |
| Pricing (per 1M tokens) | |||
| Input Pricing | $0.25 Best Input Pricing | $4 | $2 |
| Output Pricing | $2 Best Output Pricing | $20 | $10 |
| Modalities | |||
| Inputs | imagetext | textimagefile | textimagefile |
| Outputs | text | text | text |
| Benchmarks (0-100) | |||
| Intelligence Index | 20.4 | 57.6 Best Intelligence Index | 56.0 |
| Coding Index | - | - | - |
| Agentic Index | - | - | - |
Humanity's Last Exam
Extremely difficult logical reasoning and knowledge.
Long Context Reasoning
Logical reasoning over long context windows.
SciCode Benchmark
Scientific coding and mathematical modeling.
Independent evaluation data provided by Artificial Analysis. To view the latest benchmarks and full details, visit their official site.
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