GPT-5.1-Codex-Max
GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic workflows spanning software engineering, mathematics, and research. GPT-5.1-Codex-Max delivers faster performance, improved reasoning, and higher token efficiency across the development lifecycle.
Context window
This model accepts 400K tokens in one request (~300K words of text).
What fits in one request
- FitsShort documentAbout 1,500 words of text
- FitsLong documentAbout 37K words of text
- FitsSmall codebaseAbout 150K words of text
- Won't fitFull novelAbout 375K words of text
Specifications
Context size, pricing, and release info in one place.
- Context window
- 400,000 tokens (400K)
- Max output tokens
- 128,000 tokens (128K)
- Speed tier
- balanced
- Provider
- Openai
- Release date
- Dec 2025
- Input cost
- $1.25/M / 1M tokens
- Output cost
- $10.00/M / 1M tokens
- Cached input
- $0.125/M / 1M tokens
Capabilities
See which features this model supports, such as vision, tools, and streaming.
- Vision
- Accepts image inputs alongside text
- Supported
- Tool use
- Can call external tools and APIs
- Supported
- Function calling
- Structured function call interface
- Supported
- Extended thinking
- Shows its chain-of-thought reasoning
- Supported
- Streaming
- Returns tokens as they are generated
- Supported
- Prompt caching
- Reuse repeated prompt prefixes cheaply
- Supported
- Web search
- Can browse the web during a request
- Not supported
- Batch API
- Process many requests asynchronously
- Not supported
Best for
Jump to a guide or ranking that matches each workload.
Compare GPT-5.1-Codex-Max
Open a side-by-side comparison with one click.
- GPT-5.1-Codex-Max vs Amazon Titan Text Express
GPT-5.1-Codex-Max has 852% larger context window
- GPT-5.1-Codex-Max vs Amazon Titan Text Lite
GPT-5.1-Codex-Max has 852% larger context window
- GPT-5.1-Codex-Max vs Amazon Titan Text Premier
GPT-5.1-Codex-Max has 852% larger context window
- GPT-5.1-Codex-Max vs Claude Instant
GPT-5.1-Codex-Max has 300% larger context window
- GPT-5.1-Codex-Max vs Anthropic Claude
GPT-5.1-Codex-Max has 300% larger context window
- GPT-5.1-Codex-Max vs Codellama 34b Instruct
GPT-5.1-Codex-Max has 9665% larger context window
Frequently asked questions
Short answers about context size and how this model behaves.
More from Openai
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