GPT-5.1-Codex-Max is a frontier programming model built for the agent-driven era. Powered by an upgraded core reasoning architecture, it is specially trained for complex agentic tasks in software engineering, mathematics, and scientific research. It delivers faster performance, greater stability, and higher token efficiency across the entire development lifecycle, including code generation, refactoring, debugging, and engineering collaboration. With native support for multiple context windows and a built-in compaction mechanism, the model can coherently process millions of tokens within a single task.
GPT-5.1-Codex Max vs Grok 4.5
Output tokens cost $10.00 per million on GPT-5.1-Codex Max and $6.00 per million on Grok 4.5. Input tokens cost $1.25 per million on GPT-5.1-Codex Max and $2.00 per million on Grok 4.5. Cached input tokens are billed at $0.13 per million on GPT-5.1-Codex Max and $0.50 per million on Grok 4.5. Context lengths are 400,000 tokens on GPT-5.1-Codex Max and 500,000 tokens on Grok 4.5.
Grok 4.5 was trained on datasets spanning knowledge in coding, science, engineering, and math. With both intelligent and efficient reasoning, Grok 4.5 excels at real engineering tasks and exceeds comparable leading models at these tasks.
Pricing & Specifications
Prices are per million tokens. Time to First Token and throughput are rolling averages measured on AIHubMix.
Promotional prices show the discounted rate; see each model page for promotion windows.
Activity Past 30 Days
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Performance Past 3 Days
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Cost calculator
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Monthly = daily × 30. Discounted rates applied where a promotion is active.
FAQ
Which is cheaper: GPT-5.1-Codex Max, Grok 4.5?
Grok 4.5: $6.00/M output tokens; GPT-5.1-Codex Max: $10.00/M. Use the cost calculator above to estimate your own workload.
How large is each context window?
GPT-5.1-Codex Max accepts 400,000 and Grok 4.5 accepts 500,000 input tokens. Maximum output per request is 128,000 tokens on GPT-5.1-Codex Max and 500,000 tokens on Grok 4.5.
What inputs and capabilities does each model support?
GPT-5.1-Codex Max accepts text and image input and supports function calling, structured outputs and thinking; Grok 4.5 accepts text and image input and supports thinking, tool calling, function calling, structured outputs and long context.
Can I call GPT-5.1-Codex Max and Grok 4.5 with the same API key?
Yes. AIHubMix serves every model on this page behind one OpenAI-compatible endpoint, so switching between them is a one-line change to the model field — no second account, key or SDK.
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