GPT-5.1-Codex
gpt-5.1-codexGPT-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.... Built by OpenAI.
Prices updated
Input price
$1.25
per 1M tokens · Standard
Output price
$10
per 1M tokens · Standard
Input limit
400K
tokens
Output limit
128K
tokens
Input formats
Output formats
GPT-5.1-Codex price history
2 price records since 9/25/2026
GPT-5.1-Codex cost calculator
$75/month
Standard pricing
Overview
What is GPT-5.1-Codex?
GPT-5.1-Codex is a text & reasoning and vision and code & slms model from OpenAI. 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.... Its 400K context window and $1.25 input price make it a candidate for quality-focused production applications.
Benchmarks
GPT-5.1-Codex benchmarks & speed
How GPT-5.1-Codex scores on standardized evaluations, and where it lands among every model we track.
23.7
Intelligence Index
1156
DesignArena Elo
Reasoning
GPQA Diamond
86.0%
Graduate-level scientific reasoning · top 38%
HLE
25.7%
Humanity's Last Exam · top 44%
Latency & design
- DesignArena win rate
- 54.6%
- Design battles judged
- 2,005
Independent scores from Artificial Analysis and DesignArena · updated 10/8/2026. Higher is better; ranks compare against every model we track with that score.
Rates
GPT-5.1-Codex pricing
Pricing is based on token usage. Provider-specific caching, batch, regional, and tool charges may affect the final cost.
Input · Standard
$1.25
Per 1M tokens
Cached input · Standard
$0.13
Per 1M tokens
Capabilities
GPT-5.1-Codex Tools
Tools available when using GPT-5.1-Codex through supported provider APIs.
Function calling
Supported
Structured outputs
Supported
JSON mode
Supported
Reasoning
Supported
Built-in web search
Not supported
Log probabilities
Not supported
Deterministic seed
Supported
Parallel tool calls
Not supported
Prompt caching
Supported
Strengths and limitations
Strengths
- Measured results (AA Intelligence 23.7 · DesignArena Elo 1156) position it for demanding production work.
- 400K context supports large documents, repositories and extended conversations.
- Supports text & reasoning and vision and code & slms workloads in one model.
Limitations
- Generated tokens cost 8× more than input tokens, which matters for verbose responses.
- Large context capacity does not guarantee consistent retrieval across the entire prompt.
- Arena Elo and MMLU-Pro are directional; test accuracy, latency and reliability on your own workload before committing.
Arena Elo, MMLU-Pro and pricing figures are illustrative; validate current vendor terms before purchase.
Same provider