OpenAI: GPT-5.1-Codex-Max
Analysis Summary
OpenAI's GPT-5.1-Codex-Max is presented as a coding-oriented model and is listed with a 400K context window, vision, tool use, and function calling. However, this entry has no benchmark results, so its coding ability, reasoning quality, and reliability cannot be established from the supplied data.
The API features make it a plausible candidate for software workflows that involve tools or substantial code context, but those features do not substitute for measured performance. Teams should test it against their own repository tasks, including changes that require execution, debugging, and careful instruction following, before routing client work to it. No model-specific coding results are available here to support a stronger recommendation.
Listed pricing is $1.25 per million input tokens and $10 per million output tokens. Evaluate the cost alongside task success rates, and treat it as an unproven option until internal trials confirm its value.
Assessed September 23, 2026
Editorial notes
GPT-5.1-Codex-Max is listed with vision, function calling, tools, and a 400K context window, but no model-specific benchmark results are supplied to verify its coding performance.
The DFO score ranks models on the Artificial Analysis Intelligence Index and is refreshed as new models launch. The write-up and verdict are our own. Feedback?
DFO Verdict
GPT-5.1-Codex-Max is listed with vision, function calling, tools, and a 400K context window, but no model-specific benchmark results are supplied to verify its coding performance.
How OpenAI: GPT-5.1-Codex-Max compares
Its 400K-token context window is larger than 78% of the models we list. At $1.25 per million input tokens it is cheaper than 21% 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.
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.
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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.