GPT-5.1-Codex vs GPT-5 Codex
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
- ✓Higher intelligence_index of 44.6 for demanding multimodal reasoning tasks
- ✓Unified text and image reasoning with strong coding specialization
- ✓Effective handling of extremely large inputs in text and static image scenarios
Choose GPT-5 Codex if you need
- ✓Faster output speed of 178.06 t/s for high-volume generation
- ✓Strong performance on extended coding workflows without coherence loss
- ✓Effective integration of visual context with code in software development
Verdict
GPT-5 Codex leads with a higher intelligence_index of 44.6 versus 43.1, offering stronger unified text and image reasoning for complex multimodal tasks. GPT-5.1-Codex counters with superior output speed at 178.06 t/s compared to 149.9 t/s and better coherence on very large inputs. Both share identical pricing, context length, and provider, making the choice hinge on intelligence versus speed and workflow stability.
GPT-5.1-Codex vs GPT-5 Codex: side by side
| Spec | GPT-5.1-Codex | GPT-5 Codex | Winner |
|---|---|---|---|
| Intelligence | 43.1 | 44.6 | GPT-5 Codex |
| Output speed | 178 t/s | 150 t/s | GPT-5.1-Codex |
| Output price | $10.00/1M | $10.00/1M | Tie |
| Context | 400K | 400K | Tie |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | OpenAI | OpenAI | Tie |
Detailed analysis
Intelligence
Winner: GPT-5 CodexGPT-5 Codex scores 44.6 on the intelligence_index while GPT-5.1-Codex scores 43.1. This gives A an edge in overall capability for multimodal text and image tasks. Both models share the same provider and proprietary status.
Speed
Winner: GPT-5.1-CodexGPT-5.1-Codex delivers 178.06 tokens per second versus 149.9 for GPT-5 Codex. The speed advantage supports faster iteration in coding and large-input workflows. Pricing remains identical at $10 per million tokens for both.
Context Handling
Winner: GPT-5.1-CodexBoth offer 400000 context tokens, but GPT-5.1-Codex explicitly handles very large inputs without losing coherence. GPT-5 Codex notes potential coherence loss in very long outputs and higher resource demands at maximum context.
Coding Specialization
Winner: TieGPT-5 Codex emphasizes strong coding specialization and unified reasoning. GPT-5.1-Codex highlights strong performance on extended coding workflows and specialized software development tasks. Strengths overlap significantly in this area.
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
GPT-5 Codex
Pros
- +Handles extremely large inputs effectively
- +Strong coding specialization
- +Unified text and image reasoning
Cons
- –High resource demands with maximum context
- –Limited to text and static images
- –Potential coherence loss in very long outputs
Summary: GPT-5.1-Codex vs GPT-5 Codex
Select GPT-5 Codex when maximum intelligence and multimodal reasoning matter most. Choose GPT-5.1-Codex for faster outputs and reliable coherence on extended coding tasks. Both models are otherwise equivalent in price, context size, and provider.
Frequently asked questions
GPT-5 Codex is better for intelligence-driven multimodal tasks while GPT-5.1-Codex is better for speed and coherence in long coding workflows.