# Claude Sonnet 5.5 vs Grok 4.20

> Side-by-side benchmark comparison for Claude Sonnet 5.5 and Grok 4.20 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-sonnet-5-5-vs-grok-4-20-beta
- Last updated: September 28, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Sonnet 5.5 and Grok 4.20 share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Grok 4.20 has the lower published output-token price.
- Grok 4.20 has the larger published context window at 2M.

## Model Snapshot

| Property | Claude Sonnet 5.5 | Grok 4.20 |
|----------|----------|----------|
| Creator | Anthropic | xAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 2M |
| Independent public score (not head-to-head) | 80.49 | 59.76 |
| Benchmarks Covered | 47 | 23 |
| Pricing (input/output) | $2.00 / $10.00 | $1.25 / $2.50 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: 66.1 (Supported · #10/111)
- Grok 4.20 public-lane score: 23.1 (Supported · #90/111)

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 70.60% | Coming soon | Coming soon |
| HLE w/ tools | 64.5% | Coming soon | Coming soon |
| DRACO | 87.0% | Coming soon | Coming soon |
| Terminal-Bench-Science 0.1 | 59.9% | Coming soon | Coming soon |
| LAB all-pass (Harvey held-out) | 10.0% | Coming soon | Coming soon |
| LAB criterion-pass (Harvey held-out) | 93.1% | Coming soon | Coming soon |
| Toolathlon Verified Pass@3 | 85.2% | Coming soon | Coming soon |
| Toolathlon Verified Pass³ | 68.5% | Coming soon | Coming soon |
| Toolathlon Verified avg. turns | 31.6 turns | Coming soon | Coming soon |
| AutomationBench (Zapier 1.0.6) | 44.7% | Coming soon | Coming soon |
| Toolathlon-Verified | 77.8% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 47.1% | Coming soon |
| DeepSearchQA | Coming soon | 62.8% | Coming soon |
| Gert Labs | Coming soon | 38.36% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 44.2% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: 79.6 (Estimated · #3/136)
- Grok 4.20 public-lane score: 22.3 (Supported · #109/136)

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| FrontierCode 1.1 Main | 46.2% | Coming soon | Coming soon |
| cursorBench40 | 55.5% | Coming soon | Coming soon |
| SWE-bench Pro | 81.3% | 51.8% | Claude Sonnet 5.5 |
| SWE Multilingual | 90.3% | Coming soon | Coming soon |
| SWE Multimodal | 54.3% | Coming soon | Coming soon |
| DeepSWE | 71.0% | Coming soon | Coming soon |
| FrontierCode 1.1 Extended | 59.1% | Coming soon | Coming soon |
| ProgramBench | 79.7% | Coming soon | Coming soon |
| FrontierSWE v2 | 61.9% | Coming soon | Coming soon |
| LiveCodeBench Pro | Coming soon | 74.2% | Coming soon |
| SWE-bench Verified | Coming soon | 76.7% | Coming soon |
| Vibe Code Bench | Coming soon | 4.06% | Coming soon |
| LiveCodeBench (Vals) | Coming soon | 84.3% | Coming soon |
| SWE-bench (Vals) | Coming soon | 72.2% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: 79.2 (#7/27)
- Grok 4.20 public-lane score: 41.1 (Unranked · 2 rankable rows)

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 53.3% | Coming soon |
| ARC-AGI-3 | Coming soon | 0.1% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: 83.3 (Unranked · 7 rankable rows)
- Grok 4.20 public-lane score: 35.6 (#45/50)

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Chartography (no tools) | 61.6% | Coming soon | Coming soon |
| Chartography (tools) | 90.2% | Coming soon | Coming soon |
| BenchCAD Vision2Code (no tools) | 0.747 | Coming soon | Coming soon |
| BenchCAD Vision2Code (tools) | 0.963 | Coming soon | Coming soon |
| Biomedical image analysis | 72.2% | Coming soon | Coming soon |
| OfficeQA | 76.9% | Coming soon | Coming soon |
| OfficeQA Pro | 65.6% | Coming soon | Coming soon |
| MMMU-Pro | Coming soon | 75.2% | Coming soon |
| CharXiv | Coming soon | 60.9% | Coming soon |
| ERQA | Coming soon | 54.1% | Coming soon |
| SimpleVQA | Coming soon | 57.4% | Coming soon |
| MedXpertQA (MM) | Coming soon | 65.8% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: 80.9 (Supported · #6/160)
- Grok 4.20 public-lane score: 49.3 (Supported · #58/160)

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| HealthBench (raw) | 69.4% | Coming soon | Coming soon |
| HealthBench (length-adjusted) | 65.4% | Coming soon | Coming soon |
| HealthBench Professional (raw) | 77.1% | Coming soon | Coming soon |
| HealthBench Professional | 69.2% | Coming soon | Coming soon |
| BioMysteryBench (human-solvable) | 89.2% | Coming soon | Coming soon |
| BioMysteryBench (human-difficult) | 44.7% | Coming soon | Coming soon |
| SpatialBench Verified | 72.5% | Coming soon | Coming soon |
| SingleCellBench | 59.1% | Coming soon | Coming soon |
| Protein Design | 51.0% | Coming soon | Coming soon |
| Morphology-to-molecule matching | 25.0% | Coming soon | Coming soon |
| Medicinal chemistry | 65.3% | Coming soon | Coming soon |
| Protein Design library ranking | 54.8% | Coming soon | Coming soon |
| De novo protein-binder design | 82.3% | Coming soon | Coming soon |
| Protocols (troubleshooting) | 67.3% | Coming soon | Coming soon |
| Protocols (understanding) | 66.6% | Coming soon | Coming soon |
| HLE w/o tools | 56.9% | 31.6% | Claude Sonnet 5.5 |
| GPQA-D | Coming soon | 88.5% | Coming soon |
| HealthBench Hard | Coming soon | 20.3% | Coming soon |
| MedXpertQA (Text) | Coming soon | 50.2% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 88.6% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 86.3% | Coming soon |

### Multilingual

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: Coming soon
- Grok 4.20 public-lane score: Coming soon

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| GMMLU | 92.1% | Coming soon | Coming soon |
| MILU | 91.6% | Coming soon | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Claude Sonnet 5.5 public-lane score: Coming soon
- Grok 4.20 public-lane score: Coming soon

| Benchmark | Claude Sonnet 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| ArXivMath Aug. 2026 (no tools) | 86.8% | Coming soon | Coming soon |
| ArXivMath Aug. 2026 (tools) | 95.2% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Sonnet 5.5 and Grok 4.20?

Not yet. The models share only 2 sourced benchmark rows, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Claude Sonnet 5.5 vs Grok 4.20 Multi-agent](/compare/claude-sonnet-5-5-vs-grok-4-20-multi-agent-beta)
- [Grok 4.20 vs Grok 4.20 Multi-agent](/compare/grok-4-20-beta-vs-grok-4-20-multi-agent-beta)
- [Claude Sonnet 5.5 vs GPT-6 Astra](/compare/claude-sonnet-5-5-vs-gpt-6-astra)
- [Grok 4.20 vs GPT-6 Astra](/compare/gpt-6-astra-vs-grok-4-20-beta)

## Explore More

- [Claude Sonnet 5.5 profile](/models/claude-sonnet-5-5)
- [Grok 4.20 profile](/models/grok-4-20-beta)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)