GPT-5.1 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 if you need
- ✓high intelligence (44.6) for complex reasoning tasks
- ✓faster output at 149.9 t/s for efficient large-scale processing
- ✓strong coding specialization with unified text and image reasoning
- ✓effective handling of extremely large inputs
Choose GPT-5 Codex if you need
- ✓native support for images, text, and files with strong multimodal integration
- ✓very large 400k context window for extensive file processing
- ✓broader input variety beyond static images
- ✓identical pricing and context at lower speed demands
Verdict
GPT-5 Codex leads with a higher intelligence index (44.6 vs 27.4) and faster output speed (149.9 t/s vs 115.83 t/s), making it stronger for coding and unified text-image reasoning. GPT-5.1 provides native file support alongside images and text, though both share identical pricing and 400k context. Codex suits specialized high-performance needs while GPT-5.1 emphasizes broader multimodal file integration.
GPT-5.1 vs GPT-5 Codex: side by side
| Spec | GPT-5.1 | GPT-5 Codex | Winner |
|---|---|---|---|
| Intelligence | 27.4 | 44.6 | GPT-5 Codex |
| Output speed | 116 t/s | 150 t/s | GPT-5 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 compared to GPT-5.1's 27.4. This gap favors Codex for tasks requiring advanced reasoning. Both models share the same provider and proprietary status.
Speed
Winner: GPT-5 CodexCodex delivers 149.9 tokens per second versus GPT-5.1's 115.83 t/s. The speed advantage supports Codex in high-volume output scenarios. Both have the same $10 per 1M token price.
Multimodal Capabilities
Winner: GPT-5.1GPT-5.1 includes native support for images, text, and files with strong integration. Codex is limited to text and static images with coding focus. Neither supports audio or video.
Context and Pricing
Winner: TieBoth models offer 400000 context and $10 per 1M tokens. They share identical provider and proprietary nature. Resource demands and latency risks appear with maximum context in each.
GPT-5.1
Pros
- +Very large context window
- +Native support for images, text, and files
- +Strong multimodal integration
Cons
- –No audio or video modalities
- –Performance details unverified beyond specs
- –Potential latency with maximum context
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 vs GPT-5 Codex
Select GPT-5 Codex for coding-focused work needing top intelligence and speed. Choose GPT-5.1 when file processing and broader multimodal inputs are priorities. Both remain comparable on price and context size.
Frequently asked questions
GPT-5 Codex is better for intelligence and speed while GPT-5.1 is better for file-inclusive multimodal tasks; neither dominates all areas.