Claude Opus 5.5 vs Grok 4.3
Claude Opus 5.5 
Grok 4.3 Verdict
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 59.5.
- Claude Opus 5.5 (thinking) is stronger in composite, knowledge, long context, multimodal, reasoning.
- Grok 4.3 (medium) is stronger in agents & tools, instruction following.
- Grok 4.3 (medium) is 5.1× cheaper ($1.56 vs $8.00 per 1M blended).
- Grok 4.3 (medium) streams 2.1× faster (102 vs 48 tokens per second).
| Metric | Claude Opus 5.5 (thinking) | Grok 4.3 (medium) |
|---|---|---|
| BenchLeader Index | 70.7 | 59.5 |
| Composite score | 95.0 | 59.4 |
| Knowledge score | 85.0 | 71.1 |
| Long context score | 68.5 | 63.5 |
| Multimodal score | 71.9 | 59.8 |
| Reasoning score | 95.0 | 50.7 |
| Agents & tools score | – | 60.0 |
| Instruction following score | – | 80.3 |
| Blended price $/M | $8.00 | $1.56 |
| Output speed | 48 tok/s | 102 tok/s |
| Time to first answer | 4.2 s | 13.3 s |
| Context window | 1M | 1M |
| AA Intelligence Index | 57.6 | 24.8 |
| IFBench | – | 83.3% |
| AA-LCR | 84.7% | 75.0% |
| MMMU-Pro | 87.7% | 75.8% |
| AA-Omniscience | 46.4 | 16.7 |
| Terminal-Bench Hard | – | 30.3% |
| GPQA Diamond (AA) | – | 89.0% |
| Humanity's Last Exam (AA) | 61.4% | 30.0% |
| SciCode (AA) | 66.9% | – |
| τ²-Bench Telecom (AA) | – | 91.2% |
| CritPt | 31.7% | 4.9% |
| GDPval (AA) | 67.3% | – |
| Terminal-Bench 4.0 (AA) | 59.6% | – |
| AutomationBench | 69.5% | – |
| GDP.pdf | 26.2% | – |
| Harvey LAB | 91.2% | – |
| AA-Omniscience: accuracy | 66.2% | 28.8% |
| AA-Omniscience: non-hallucination | 41.4% | 83.1% |
| AA-Briefcase | 1822 | – |
Data as of 2026-09-22. Best configuration of each model; every score links to its source on the model pages.
Claude Opus 5.5 vs Grok 4.3: questions
- Is Claude Opus 5.5 better than Grok 4.3?
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 59.5. The BenchLeader Index combines every independent quality benchmark; Claude Opus 5.5 (thinking) is ahead overall as of 2026-09-22, but check the category scores for your use.
- Which is cheaper, Claude Opus 5.5 or Grok 4.3?
- Grok 4.3 is cheaper: $1.56 against $8.00 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 5.5 or Grok 4.3?
- Grok 4.3 streams faster: 102 against 48 output tokens per second.
- Which has the larger context window?
- Both accept 1M tokens of context.