GPT-5.5 Pro vs Grok 4.3
GPT-5.5 Pro 
Grok 4.3 Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 59.9.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- Grok 4.3 (medium) is stronger in agents & tools, composite, instruction following, knowledge, long context, multimodal.
- Grok 4.3 (medium) is 43× cheaper ($1.56 vs $67.50 per 1M blended).
- Grok 4.3 (medium) streams 25.1× faster (101 vs 4 tokens per second).
| Metric | GPT-5.5 Pro (xhigh) | Grok 4.3 (medium) |
|---|---|---|
| BenchLeader Index | 67.1 | 59.9 |
| Maths score | 74.5 | – |
| Reasoning score | 80.1 | 51.4 |
| Agents & tools score | – | 60.0 |
| Composite score | – | 60.4 |
| Instruction following score | – | 80.3 |
| Knowledge score | – | 72.2 |
| Long context score | – | 63.9 |
| Multimodal score | – | 60.3 |
| Blended price $/M | $67.50 | $1.56 |
| Output speed | 4 tok/s | 101 tok/s |
| Time to first answer | 3.5 s | 14.8 s |
| Context window | 1.1M | 1M |
| FrontierMath Tiers 1–3 | 87.7% | – |
| FrontierMath Tier 4 | 78.0% | – |
| AA Intelligence Index | – | 24.8 |
| IFBench | – | 83.3% |
| AA-LCR | – | 75.0% |
| MMMU-Pro | – | 75.8% |
| AA-Omniscience | – | 16.7 |
| Terminal-Bench Hard | – | 30.3% |
| GPQA Diamond (AA) | – | 89.0% |
| Humanity's Last Exam (AA) | – | 30.0% |
| τ²-Bench Telecom (AA) | – | 91.2% |
| ARC-AGI-1 | 95.0% | – |
| ARC-AGI-2 | 84.2% | – |
| CritPt | 30.6% | 4.9% |
| LMCA | 53.9% | – |
| DTBench | 96.0% | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Pro vs Grok 4.3: questions
- Is GPT-5.5 Pro better than Grok 4.3?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 59.9. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Which is cheaper, GPT-5.5 Pro or Grok 4.3?
- Grok 4.3 is cheaper: $1.56 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Pro or Grok 4.3?
- Grok 4.3 streams faster: 101 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 1M tokens.