OpenAI: GPT-5.1-Codex
Analysis Summary
GPT-5.1-Codex is OpenAI's coding-focused variant in the GPT-5.1 family, with an intelligence index of 43.1 and a coding index of 36.6. GPQA at 0.860 and livecodebench at 0.849 confirm strong reasoning and code generation capability. Vision, tool use, function calling, and a 400K context window make it a versatile option for technical business workflows.
For businesses, this model suits software engineering assistance, code review, agentic task execution, and long-document analysis. The agentic index of 58.9 and terminalbench hard score of 0.348 support multi-step tool use. Its coding index trails the broader GPT-5.1, suggesting the Codex branding reflects a specialisation in reasoning-heavy code tasks rather than raw coding throughput.
At $1.25 input and $10.00 output, pricing matches GPT-5.1. Teams focused on coding and agentic workflows will find this a strong option, though the benchmarked GPT-5.1 edges it on overall intelligence and agentic scores.
Assessed June 6, 2026
Editorial notes
GPT-5.1-Codex from OpenAI combines strong reasoning with vision, tool use, and a 400K context window, delivering reliable performance across coding and agentic workflows.
Rankings consider pricing, capabilities, benchmarks, and real-world applicability and are refreshed as new models launch. Feedback?
Performance Profile
How OpenAI: GPT-5.1-Codex compares
OpenAI: GPT-5.1-Codex ranks #43 of 377 AI models we track for overall intelligence, #56 of 314 for coding, #60 of 289 for agentic tasks. Its 400K-token context window is larger than 85% of the models we list. At $1.25 per million input tokens it is cheaper than 21% of comparable models.
About OpenAI: GPT-5.1-Codex
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks..
Capabilities
Performance Indices
Source: Artificial Analysis
Benchmark Scores
Intelligence
Technical
Content
Benchmark data from Artificial Analysis and Hugging Face
How does OpenAI: GPT-5.1-Codex stack up?
Compare side-by-side with other professional models.
Model Information
| OpenRouter ID |
openai/gpt-5.1-codex
|
| Provider | openai |
| Release Date | November 13, 2025 |
| Context Length | 400,000 tokens |
| Max Completion | 128,000 tokens |
| Status | Active |
Pricing
| Token Type | Cost per 1M tokens | Cost per 1K tokens |
|---|---|---|
| Input | $1.25 | $0.001250 |
| Output | $10.00 | $0.010000 |
Live Performance
Live endpoint metrics, refreshed every 30 minutes.
Leaderboard Categories
External Resources
Frequently asked questions about OpenAI: GPT-5.1-Codex
How much does OpenAI: GPT-5.1-Codex cost?
OpenAI: GPT-5.1-Codex costs $1.25 per million input tokens and $10.00 per million output tokens.
What is the context window of OpenAI: GPT-5.1-Codex?
OpenAI: GPT-5.1-Codex has a context window of 400,000 tokens (400K).
Is OpenAI: GPT-5.1-Codex good for coding?
On our coding benchmark index, OpenAI: GPT-5.1-Codex ranks #56 of 314 models, placing it in the top quartile of the field for code generation and debugging.
What can OpenAI: GPT-5.1-Codex do?
OpenAI: GPT-5.1-Codex supports image/vision input, tool use, and function calling.
Who created OpenAI: GPT-5.1-Codex?
OpenAI: GPT-5.1-Codex is developed by OpenAI and was released on November 13, 2025.
