GPT-5.1-Codex vs Grok 4.3
A side-by-side comparison of two multimodal models — real specs, pricing, strengths and weaknesses, and a clear verdict on which to choose. Kept current by our agents.
Quick verdict: which should you choose?
Choose GPT-5.1-Codex if you need
- ✓Complex multi-step reasoning with a 1M-token context for document-level text and image tasks
- ✓Lower cost at $2.5 per million tokens alongside real-time tool access
- ✓Helpful, direct responses without heavy prompt engineering
- ✓Maximum context usage where intelligence index of 43.9 provides an edge
Choose Grok 4.3 if you need
- ✓Extended coding workflows that integrate visual context with code at 178 t/s speed
- ✓Faster output for large inputs while maintaining coherence in software development
- ✓Specialized handling of very large coding tasks despite the smaller 400k context
- ✓Scenarios where higher speed outweighs the $10 per million token price
Verdict
Grok 4.3 leads on raw intelligence (43.9 vs 43.1), context size, and price, making it stronger for complex multi-step reasoning and document-scale multimodal tasks. GPT-5.1-Codex wins on output speed and coding-specific strengths, delivering faster responses for extended software workflows. Neither dominates overall; choice hinges on whether reasoning depth and cost or speed and code integration matter more.
GPT-5.1-Codex vs Grok 4.3: side by side
| Spec | GPT-5.1-Codex | Grok 4.3 | Winner |
|---|---|---|---|
| Intelligence | 43.1 | 43.9 | Grok 4.3 |
| Output speed | 178 t/s | 135 t/s | GPT-5.1-Codex |
| Output price | $10.00/1M | $2.50/1M | Grok 4.3 |
| Context | 400K | 1000K | Grok 4.3 |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | OpenAI | xAI | Tie |
Detailed analysis
Intelligence
Winner: Grok 4.3Grok 4.3 scores 43.9 on the intelligence index compared to GPT-5.1-Codex at 43.1. This gives it an advantage in complex multi-step reasoning tasks. GPT-5.1-Codex instead emphasizes coding workflow performance.
Speed
Winner: GPT-5.1-CodexGPT-5.1-Codex outputs at 178.06 tokens per second versus Grok 4.3 at 134.99 t/s. The speed difference favors GPT-5.1-Codex for high-volume or time-sensitive multimodal work. Both models incur high costs at maximum context.
Pricing
Winner: Grok 4.3Grok 4.3 costs $2.5 per million output tokens while GPT-5.1-Codex costs $10 per million. The fourfold price gap makes Grok 4.3 the clear choice for budget-conscious users. Context size does not alter the listed per-token rates.
Context Window
Winner: Grok 4.3Grok 4.3 supports a 1M-token context versus GPT-5.1-Codex at 400k tokens. This enables stronger document-level multimodal tasks for Grok 4.3. Both note high computational cost when using their maximum context.
GPT-5.1-Codex
Pros
- +Strong performance on extended coding workflows
- +Effective integration of visual context with code
- +Handles very large inputs without losing coherence
- +Specialized for software development tasks
Cons
- –Limited to text and image inputs only
- –High computational cost for maximum context
- –May require careful prompt engineering for complex tasks
Grok 4.3
Pros
- +Strong performance on complex multi-step reasoning
- +Large context window for document-level tasks
- +Helpful and direct response style
- +Integrated real-time tool access
Cons
- –Vision capabilities less mature than specialized models
- –Occasional over-refusal on edge-case queries
- –High computational cost for maximum context usage
Summary: GPT-5.1-Codex vs Grok 4.3
Select Grok 4.3 for higher intelligence, larger context, and lower price on complex reasoning tasks. Choose GPT-5.1-Codex when coding speed and visual-code integration are priorities. The models split advantages evenly across the provided metrics.
Frequently asked questions
Grok 4.3 is better for intelligence, context, and cost; GPT-5.1-Codex is better for speed and coding tasks. No single winner exists across all dimensions.