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Step 5 Preview
GPT-5.1-Codex
GPT-5.1-Codex is a proprietary model from OpenAI, released Nov 13, 2025. Its best result is #31 of 143 on LiveCodeBench with 85.55%. It costs $1.25 per million input tokens and $10 per million output tokens, with a 400K-token context window.
- Developer
- OpenAI
- Released
- Nov 13, 2025
- Context window
- 400K
- Price in / out, per 1M tokens
- $1.25 / $10
- Weights
- Proprietary
- Inputs
- Text, Images
- Reasoning
- Yes
- Tool use
- Yes
Benchmarks
| Benchmark | Score bar | Accuracy | Rank | Cost / test |
|---|---|---|---|---|
| Vibe Code BenchCoding | 13.12% | 94 / 115 | $3.80 | |
| LiveCodeBenchCoding | 85.55% | 31 / 143 | $1.25 / $10 |
Vals AI, as of Oct 24, 2026.
LMArena, by category
| Leaderboard | Rating | Rank | Votes |
|---|---|---|---|
| WebDevLMArena | 1337 | 124 / 124 | 5K |
LMArena, CC BY 4.0, as of Oct 22, 2026. Where a model is rated at several effort levels, its best is shown.
Compare GPT-5.1-Codex
OpenAI
The lab behind GPT and ChatGPT, which brought large language models to hundreds of millions of people. Founded 2015, based in San Francisco. openai.com
Questions
Who makes GPT-5.1-Codex?
GPT-5.1-Codex is made by OpenAI, founded 2015 and based in San Francisco.
How much does GPT-5.1-Codex cost?
$1.25 per million input tokens and $10 per million output tokens, at its provider’s list price.
What is GPT-5.1-Codex’s context window?
400K tokens (400,000).
Is GPT-5.1-Codex open source?
No. GPT-5.1-Codex is proprietary and served through its provider’s API.