OpenAI: GPT-5.1-Codex-Max
Analysis Summary
OpenAI's GPT-5.1-Codex-Max is a coding-focused multimodal model with a 400,000-token context window, vision, tool use, and function calling. These capabilities are well matched to large repositories, visual development tasks, and API-connected engineering workflows. However, this specific variant has no supplied benchmark evidence, so its coding reliability and agentic performance cannot be established from the dataset.
The product profile makes it a candidate for codebase analysis, implementation assistance, test generation, and supervised engineering agents. Its output price is high, which argues against routine bulk generation and favours high-value tasks where context and depth matter. Run a controlled pilot with repository-level evaluations before committing it to client delivery. It is a promising specialist option, not a proven default.
Assessed August 9, 2026
Editorial notes
GPT-5.1-Codex-Max is positioned for coding with a 400K context window, vision, tools, and function calling. No benchmark results are supplied for this variant, while its output price is high, so adoption should begin with targeted engineering pilots.
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DFO Verdict
GPT-5.1-Codex-Max is positioned for coding with a 400K context window, vision, tools, and function calling. No benchmark results are supplied for this variant, while its output price is high, so adoption should begin with targeted engineering pilots.
How OpenAI: GPT-5.1-Codex-Max compares
Its 400K-token context window is larger than 76% of the models we list. At $1.25 per million input tokens it is cheaper than 23% of comparable models.
Dark bar = input · light bar = output, scaled to the priciest peer.
1M tokens ≈ 8 full-length novels or ~2,500 pages of business documents in a single request.
Strongest on value. The pulled-in technical corner is the trade-off, and if the shape matters more than the price, this is your model.
Compare shapes side-by-side →Pricing
| Token Type | Cost per 1M tokens | Cost per 1K tokens |
|---|---|---|
| Input | $1.25 | $0.001250 |
| Output | $10.00 | $0.010000 |
What would OpenAI: GPT-5.1-Codex-Max cost your business?
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A website chatbot handling around 100 customer conversations a day, a few short messages each.
Full calculator with 743 models → Price Calculator
These numbers get smaller with the right architecture.
We route routine calls to cheap models and save OpenAI: GPT-5.1-Codex-Max for the hard ones. Most clients cut their estimate by 60-80%.
Talk to our teamAbout OpenAI: 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..
Frequently asked questions about OpenAI: GPT-5.1-Codex-Max
How much does OpenAI: GPT-5.1-Codex-Max cost?
OpenAI: GPT-5.1-Codex-Max 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-Max?
OpenAI: GPT-5.1-Codex-Max has a context window of 400,000 tokens (400K).
What can OpenAI: GPT-5.1-Codex-Max do?
OpenAI: GPT-5.1-Codex-Max supports image/vision input, tool use, and function calling.
Who created OpenAI: GPT-5.1-Codex-Max?
OpenAI: GPT-5.1-Codex-Max is developed by OpenAI and was released on December 4, 2025.