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Grok 4.5 vs GPT 5.1 Codex Max

At a glance
xAIGrok 4.5

xAI's Opus-class flagship for frontier coding, agentic tool use, and knowledge work.

89500K ctx$2.00/$6.00 per M#6/92
OpenAIGPT 5.1 Codex Max

Extended-context coding model for large codebase operations.

400K ctx$1.25/$10.00 per M
AI Output
All AI outputs

No captured outputs for these models yet.

Benchmarks
See rankings
xAIGrok 4.5
Reasoning
CI 86.2-90.3
CodingInsufficient data
Sources:Epoch ECI·Epoch AI·Provider·OpenRouter· as of 2026-07-10
Cheaper
Capability
CapabilityECI88.5
Reasoning & Knowledge
Graduate Science93.4%Factual Recall53.5%
Math
Competition Math97.8%
Agentic
Terminal Tasks83.3%Task Horizon—
OpenAIGPT 5.1 Codex Max
Reasoning
CodingInsufficient data
ReasoningInsufficient data
MathInsufficient data
Sources:Epoch AI·OpenRouter· as of 2026-07-10
Capability
Capability—
Reasoning & Knowledge
Graduate Science—Factual Recall—
Math
Competition Math—
Agentic
Terminal Tasks60.4%Task Horizon2.7h
Specs
xAIGrok 4.5
500K
Context
16K
Max output
Jul 2026
Released
OpenAIGPT 5.1 Codex Max
400K
Context
128K
Max output
Dec 2025
Released
Capabilities
xAIGrok 4.5
Vision
Audio
Reasoning
OpenAIGPT 5.1 Codex Max
Vision
Audio
Reasoning
Pricing
xAIGrok 4.5
Live pricing, shown before you run
Input$2.00/M tokens
Output$6.00/M tokens
Cache read$0.50/M tokens
Web search$0.005/search
OpenAIGPT 5.1 Codex Max
Live pricing, shown before you run
Input$1.25/M tokens
Output$10.00/M tokens
Cache read$0.13/M tokens
Web search$0.01/search
Chat with Grok 4.5Go to model
Chat with GPT 5.1 Codex MaxGo to model
Frequently Asked Questions: Grok 4.5 vs GPT 5.1 Codex Max▼

Which is better, Grok 4.5 or GPT 5.1 Codex Max?

▼

Both Grok 4.5 and GPT 5.1 Codex Max are capable AI models. The best choice depends on your specific use case: consider pricing, context window, speed, and which capabilities (vision, reasoning, audio) you need.

Which is cheaper, Grok 4.5 or GPT 5.1 Codex Max?

▼

Grok 4.5 has a lower blended cost. Grok 4.5: $2.00 input / $6.00 output. GPT 5.1 Codex Max: $1.25 input / $10.00 output.

Which has a larger context window, Grok 4.5 or GPT 5.1 Codex Max?

▼

Grok 4.5 has a larger context window: Grok 4.5 supports 500K tokens vs GPT 5.1 Codex Max at 400K tokens.

Do both Grok 4.5 and GPT 5.1 Codex Max support vision?

▼

Yes, both Grok 4.5 and GPT 5.1 Codex Max support vision/image input.

What are the key differences between Grok 4.5 and GPT 5.1 Codex Max?

▼

Grok 4.5 and GPT 5.1 Codex Max have similar overall capabilities. The main differences lie in pricing, context window size, and provider-specific strengths. Use this comparison page to review all metrics side by side.

Which model should I choose for my use case?

▼

If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both Grok 4.5 and GPT 5.1 Codex Max for free on idapt.app to see which performs better for your specific needs.

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