Claude Sonnet 5.5 vs Grok 4.20
Claude Sonnet 5.5 
Grok 4.20 Verdict
- Claude Sonnet 5.5 (max) leads on quality: 67.6 vs 59.0.
- Claude Sonnet 5.5 (max) is stronger in agents & tools, coding, composite, knowledge, long context, maths, reasoning.
- Grok 4.20 (thinking) is stronger in human preference, instruction following, multimodal.
- Grok 4.20 (thinking) is 1.3× cheaper ($3.00 vs $4.00 per 1M blended).
- Claude Sonnet 5.5 (max) streams 1.4× faster (141 vs 103 tokens per second).
| Metric | Claude Sonnet 5.5 (max) | Grok 4.20 (thinking) |
|---|---|---|
| BenchLeader Index | 67.6 | 59.0 |
| Agents & tools score | 69.5 | 51.7 |
| Coding score | 69.8 | 53.9 |
| Composite score | 72.6 | 58.5 |
| Knowledge score | 65.4 | 56.2 |
| Long context score | 66.6 | 59.5 |
| Maths score | 72.9 | 54.4 |
| Reasoning score | 81.1 | 59.4 |
| Human preference score | – | 66.6 |
| Instruction following score | – | 79.9 |
| Multimodal score | – | 58.8 |
| Blended price $/M | $4.00 | $3.00 |
| Output speed | 141 tok/s | 103 tok/s |
| Time to first answer | 487.1 s | 18.5 s |
| Context window | 1M | 2M |
| GPQA Diamond | 95.6% | 89.3% |
| FrontierMath Tiers 1–3 | 88.8% | 44.9% |
| FrontierMath Tier 4 | 80.5% | 17.1% |
| OTIS Mock AIME | 100.0% | 92.2% |
| SimpleQA Verified | 46.5% | 30.2% |
| Terminal-Bench | 61.8% | – |
| SciCode | 61.0% | – |
| APEX-Agents | 75.5% | – |
| ProofBench | 100.0% | 14.0% |
| LMArena Text | – | 1472 |
| LMArena Hard Prompts | – | 1489 |
| LMArena Coding | – | 1511 |
| LMArena WebDev | – | 1375 |
| LMArena Vision | – | 1263 |
| LMArena Agent | 12 | – |
| LiveBench | 75.7% | – |
| LiveBench Reasoning | 91.6% | – |
| LiveBench Coding | 91.4% | – |
| LiveBench Agentic Coding | 56.3% | – |
| LiveBench Mathematics | 96.1% | – |
| LiveBench Data Analysis | 59.5% | – |
| LiveBench Language | 78.0% | – |
| LiveBench Instruction Following | 56.8% | – |
| AA Intelligence Index v4.3.2 | 56 | 25.7 |
| IFBench | – | 82.9% |
| AA-LCR | 82.7% | 69.0% |
| MMMU-Pro | – | 74.6% |
| AA-Omniscience | 32.3 | 14.8 |
| Terminal-Bench Hard | – | 40.9% |
| GPQA Diamond (AA) | – | 91.1% |
| Humanity's Last Exam (AA) | 55.0% | 34.5% |
| SciCode (AA) | 61.0% | – |
| τ²-Bench Telecom (AA) | – | 96.5% |
| AIME (Vals) | – | 96.5% |
| LiveCodeBench | – | 84.3% |
| MMLU-Pro | – | 86.3% |
| LegalBench | – | 77.7% |
| CorpFin | – | 63.7% |
| TaxEval | – | 74.1% |
| MedQA | – | 94.5% |
| Terminal-Bench 2.1 (Vals) | – | 44.2% |
| SWE-bench (Vals) | – | 72.2% |
| GPQA Diamond (Vals) | – | 88.6% |
| Kagi LLM Benchmark | – | 75.0% |
| ARC-AGI-1 | – | 89.5% |
| ARC-AGI-2 | – | 65.1% |
| ARC-AGI-3 | – | 0.1% |
| CritPt | 31.4% | 6.6% |
| GDPval-AA v2.1 | 67.0% | – |
| Analyst Agent (AA) | 57.5% | – |
| APEX-Agents (AA) | – | 14.2% |
| CaseLaw v2 | – | 54.5% |
| Code Migration | – | 0.3% |
| Excel Modeling Benchmark | – | 11.7% |
| Finance Agent v2 | – | 28.5% |
| Harvey's Legal Agent Benchmark | – | 0.0% |
| Legal Research Bench | – | 13.9% |
| MedCode | – | 32.2% |
| MedScribe | – | 63.4% |
| MMMU-Pro (Vals) | – | 83.5% |
| MortgageTax | – | 45.4% |
| SAGE | – | 38.2% |
| Tax Agent Bench | – | 31.2% |
| Terminal-Bench 2.0 (Vals) | – | 40.5% |
| Vals Multimodal Index | – | 39.1% |
| Vibe Code Bench v1.1 | – | 4.1% |
| LMArena Maths | – | 1465 |
| LMArena Creative Writing | – | 1445 |
| LMArena Instruction Following | – | 1447 |
| LMArena Multi-turn | – | 1479 |
| LMArena Longer Queries | – | 1466 |
| LMArena Document | – | 1439 |
| Chess Puzzles | – | 24.0% |
| Mystery Game Puzzles | 65.0% | – |
| ForecastBench | – | 60.7% |
| CursorBench | 55.5% | – |
| FrontierSWE | 61.9% | – |
| Terminal-Bench 4.0 (AA) | 63.6% | – |
| AutomationBench | 71.8% | – |
| GDP.pdf | 25.8% | – |
| MLCR | 75.0% | – |
| Harvey LAB | 2.8% | – |
| AA-Omniscience: accuracy | 54.0% | 28.9% |
| AA-Omniscience: non-hallucination | 53.0% | 82.6% |
| AA-Briefcase v1.1 | 1823 | – |
Data as of 2026-10-11. Best configuration of each model; every score links to its source on the model pages.
Claude Sonnet 5.5 vs Grok 4.20: questions
- Is Claude Sonnet 5.5 better than Grok 4.20?
- Claude Sonnet 5.5 (max) leads on quality: 67.6 vs 59.0. The BenchLeader Index combines every independent quality benchmark; Claude Sonnet 5.5 (max) is ahead overall as of 2026-10-11, but check the category scores for your use.
- Is Claude Sonnet 5.5 better than Grok 4.20 for coding?
- Claude Sonnet 5.5 scores higher in coding (70 vs 54 on the category index, where 50 is average).
- Is Claude Sonnet 5.5 better than Grok 4.20 for agentic tasks?
- Claude Sonnet 5.5 scores higher in agentic tasks (70 vs 52 on the category index, where 50 is average).
- Which is cheaper, Claude Sonnet 5.5 or Grok 4.20?
- Grok 4.20 is cheaper: $3.00 against $4.00 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Sonnet 5.5 or Grok 4.20?
- Claude Sonnet 5.5 streams faster: 141 against 103 output tokens per second.
- Which has the larger context window?
- Grok 4.20 accepts more context: 2M against 1M tokens.