GPT-5.5 Pro 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-5.5 Pro if you need
- ✓Choose GPT-5.5 Pro if you need a 1.05M-token context window with native file, image, and text support.
- ✓Choose GPT-5.5 Pro if you need seamless multimodal integration and strong reasoning over very long combined inputs.
- ✓Choose GPT-5.5 Pro if you prioritize maximum context capacity over cost or measured speed.
Choose Grok 4.3 if you need
- ✓Choose Grok 4.3 if you need dramatically lower output pricing at $2.5 per million tokens versus $180.
- ✓Choose Grok 4.3 if you need documented high output speed of 135.7 tokens per second.
- ✓Choose Grok 4.3 if you need integrated real-time tool access alongside 1M-token context for multi-step reasoning.
Verdict
GPT-5.5 Pro leads in raw context size and native multimodal file/image/text integration with seamless handling of extended inputs, while Grok 4.3 leads decisively on price and documented output speed. GPT-5.5 Pro suits workloads needing maximum context and polished multimodal fusion; Grok 4.3 suits cost-sensitive, high-throughput reasoning tasks. Neither model discloses parameter count or intelligence index for direct comparison.
GPT-5.5 Pro vs Grok 4.3: side by side
| Spec | GPT-5.5 Pro | Grok 4.3 | Winner |
|---|---|---|---|
| Intelligence | — | 35.4 | Tie |
| Output speed | — | 136 t/s | Tie |
| Output price | $180.00/1M | $2.50/1M | Grok 4.3 |
| Context | 1050K | 1000K | GPT-5.5 Pro |
| Params | — | — | Tie |
| Provider | OpenAI | xAI | Tie |
Detailed analysis
Context Window
Winner: GPT-5.5 ProGPT-5.5 Pro offers 1,050,000 tokens compared with Grok 4.3's 1,000,000 tokens. Both support large document-level tasks, yet GPT-5.5 Pro holds a modest edge in maximum length.
Pricing
Winner: Grok 4.3Grok 4.3 is priced at $2.5 per million output tokens while GPT-5.5 Pro costs $180 per million. The 72-fold price difference makes Grok 4.3 far more economical for high-volume use.
Multimodal Capabilities
Winner: GPT-5.5 ProGPT-5.5 Pro provides native support for files, images, and text with seamless integration. Grok 4.3 handles text and image tasks but notes its vision capabilities are less mature than specialized models.
Speed & Throughput
Winner: Grok 4.3Grok 4.3 reports a measured output speed of 135.7 tokens per second. No speed figure is available for GPT-5.5 Pro, which lists potential latency on maximum-length inputs as a limitation.
GPT-5.5 Pro
Pros
- +Very large context window
- +Native support for files, images, and text
- +Seamless multimodal integration
Cons
- –High resource use with maximum context
- –No audio or video modalities
- –Potential latency on very long inputs
Grok 4.3
Pros
- +Strong performance on complex multi-step reasoning
- +Large context window for document-level tasks
- +Helpful and direct response style
Cons
- –Vision capabilities less mature than specialized models
- –Occasional over-refusal on edge-case queries
- –High computational cost for maximum context usage
Summary: GPT-5.5 Pro vs Grok 4.3
Select GPT-5.5 Pro when maximum context length and polished multimodal file handling are primary requirements. Select Grok 4.3 when price, speed, and real-time tooling matter more than the extra 50k tokens or deeper multimodal fusion. Both remain proprietary models with undisclosed parameter counts.
Frequently asked questions
GPT-5.5 Pro is stronger for seamless multimodal integration and largest context, while Grok 4.3 is stronger on price and speed; choice depends on whether integration depth or cost-efficiency is prioritized.