Claude Opus 5.5 vs Grok 4.5
Claude Opus 5.5 
Grok 4.5 Verdict
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 60.6.
- Claude Opus 5.5 (thinking) is stronger in composite, knowledge, long context, multimodal, reasoning.
- Grok 4.5 (high) is stronger in agents & tools, coding, maths.
- Grok 4.5 (high) is 2.7× cheaper ($3.00 vs $8.00 per 1M blended).
| Metric | Claude Opus 5.5 (thinking) | Grok 4.5 (high) |
|---|---|---|
| BenchLeader Index | 70.7 | 60.6 |
| Composite score | 95.0 | 76.5 |
| Knowledge score | 85.0 | 63.4 |
| Long context score | 68.5 | 65.8 |
| Multimodal score | 71.9 | 64.4 |
| Reasoning score | 95.0 | 61.9 |
| Agents & tools score | – | 50.2 |
| Coding score | – | 57.7 |
| Maths score | – | 55.3 |
| Blended price $/M | $8.00 | $3.00 |
| Output speed | 48 tok/s | 55 tok/s |
| Time to first answer | 4.2 s | 10.6 s |
| Context window | 1M | 500k |
| GPQA Diamond | – | 93.4% |
| FrontierMath Tiers 1–3 | – | 57.2% |
| FrontierMath Tier 4 | – | 24.4% |
| OTIS Mock AIME | – | 97.8% |
| SimpleQA Verified | – | 48.3% |
| Terminal-Bench | – | 12.4% |
| SciCode | – | 54.0% |
| ProofBench | – | 31.0% |
| AA Intelligence Index | 57.6 | 38.8 |
| AA-LCR | 84.7% | 79.3% |
| MMMU-Pro | 87.7% | 80.4% |
| AA-Omniscience | 46.4 | 25.3 |
| GPQA Diamond (AA) | – | 93.1% |
| Humanity's Last Exam (AA) | 61.4% | 42.7% |
| SciCode (AA) | 66.9% | 55.0% |
| LiveCodeBench | – | 87.3% |
| MMLU-Pro | – | 89.2% |
| IOI | – | 40.6% |
| LegalBench | – | 86.0% |
| CorpFin | – | 67.4% |
| TaxEval | – | 71.7% |
| Terminal-Bench 2.1 (Vals) | – | 67.8% |
| SWE-bench (Vals) | – | 86.6% |
| GPQA Diamond (Vals) | – | 92.9% |
| Vals Index | – | 51.5 |
| ARC-AGI-1 | – | 85.7% |
| ARC-AGI-2 | – | 52.6% |
| ARC-AGI-3 | – | 0.3% |
| CritPt | 31.7% | 15.4% |
| GDPval (AA) | 67.3% | 43.5% |
| τ²-Bench Banking (AA) | – | 42.1% |
| Analyst Agent (AA) | – | 35.0% |
| Code Migration | – | 36.6% |
| Excel Modeling Benchmark | – | 52.9% |
| Finance Agent v2 | – | 48.4% |
| Harvey's Legal Agent Benchmark | – | 12.9% |
| Legal Research Bench | – | 38.0% |
| MedCode | – | 43.3% |
| MedScribe | – | 86.9% |
| MMMU-Pro (Vals) | – | 61.8% |
| MortgageTax | – | 61.8% |
| ProgramBench | – | 0.0% |
| SAGE | – | 35.0% |
| SkillsBench | – | 66.0% |
| SREBench | – | 0.8% |
| Terminal-Bench 4.0 (Vals) | – | 6.6% |
| Time Horizon Index: KSP | – | 6.3% |
| Vals Multimodal Index | – | 63.4% |
| Vibe Code Bench v1.1 | – | 69.0% |
| Web Search Index | – | 35.5% |
| Chess Puzzles | – | 36.0% |
| PostTrainBench | – | 23.4% |
| Surface Evolver Bench | – | 74.4% |
| DeepSWE | – | 53.8% |
| LMCA | – | 45.2% |
| DTBench | – | 96.5% |
| ALE-Bench | – | 1309.3 |
| GDP.pdf | – | 14.0% |
| Terminal-Bench 4.0 (AA) | 59.6% | 10.6% |
| Terminal-Bench 2.1 (AA) | – | 81.7% |
| AutomationBench | 69.5% | – |
| GDP.pdf | 26.2% | – |
| Harvey LAB | 91.2% | – |
| AA-Omniscience: accuracy | 66.2% | 51.5% |
| AA-Omniscience: non-hallucination | 41.4% | 45.9% |
| 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 4.5: questions
- Is Claude Opus 5.5 better than Grok 4.5?
- Claude Opus 5.5 (thinking) leads on quality: 70.7 vs 60.6. 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 4.5?
- Grok 4.5 is cheaper: $3.00 against $8.00 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 5.5 or Grok 4.5?
- Grok 4.5 streams faster: 55 against 48 output tokens per second.
- Which has the larger context window?
- Claude Opus 5.5 accepts more context: 1M against 500k tokens.