# Claude Opus 5.5 vs Grok 4.20

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

- Canonical page: https://benchlm.ai/compare/claude-opus-5-5-vs-grok-4-20-beta
- Last updated: September 22, 2026

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

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Opus 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 Opus 5.5 | Grok 4.20 |
|----------|----------|----------|
| Creator | Anthropic | xAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 2M |
| Independent public score (not head-to-head) | 81.03 | 67.97 |
| Benchmarks Covered | 47 | 23 |
| Pricing (input/output) | $4.00 / $20.00 | $2.00 / $6.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Opus 5.5 public-lane score: 82.9 (Supported · #1/157)
- Grok 4.20 public-lane score: 29.5 (Supported · #147/157)

| Benchmark | Claude Opus 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 66.40% | Coming soon | Coming soon |
| Terminal-Bench-Science 0.1 | 58.7% | Coming soon | Coming soon |
| AutomationBench | 40.0% | Coming soon | Coming soon |
| HLE w/ tools | 67.7% | Coming soon | Coming soon |
| OSWorld 2.0 | 48.7% | Coming soon | Coming soon |
| LAB all-pass (Harvey held-out) | 8.3% | Coming soon | Coming soon |
| LAB criterion-pass (Harvey held-out) | 91.2% | Coming soon | Coming soon |
| Toolathlon-Verified | 77.8% | Coming soon | Coming soon |
| Toolathlon Verified Pass@3 | 82.4% | Coming soon | Coming soon |
| Toolathlon Verified Pass³ | 72.2% | Coming soon | Coming soon |
| Toolathlon Verified avg. turns | 26.9 turns | 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 Opus 5.5 public-lane score: 80.1 (Supported · #2/159)
- Grok 4.20 public-lane score: 29.8 (Supported · #149/159)

| Benchmark | Claude Opus 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| FrontierCode 1.1 Main | 54.4% | Coming soon | Coming soon |
| cursorBench40 | 57.8% | Coming soon | Coming soon |
| SWE-bench Pro | 89.9% | 51.8% | Claude Opus 5.5 |
| SWE Multilingual | 93.9% | Coming soon | Coming soon |
| SWE Multimodal | 61.4% | Coming soon | Coming soon |
| DeepSWE | 74.2% | Coming soon | Coming soon |
| FrontierCode 1.1 Extended | 63.6% | Coming soon | Coming soon |
| FrontierSWE v2 | 62.3% | Coming soon | Coming soon |
| ProgramBench | 91.2% | 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 Opus 5.5 public-lane score: 78.5 (#4/17)
- Grok 4.20 public-lane score: 34.3 (Unranked · 2 rankable rows)

| Benchmark | Claude Opus 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 Opus 5.5 public-lane score: 88.8 (#3/50)
- Grok 4.20 public-lane score: 34.6 (#45/50)

| Benchmark | Claude Opus 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Chartography (tools) | 89.0% | Coming soon | Coming soon |
| Chartography (no tools) | 64.4% | Coming soon | Coming soon |
| BenchCAD Vision2Code (no tools) | 0.730 | Coming soon | Coming soon |
| BenchCAD Vision2Code (tools) | 0.962 | Coming soon | Coming soon |
| Biomedical image analysis | 71.4% | Coming soon | Coming soon |
| OfficeQA | 78.9% | Coming soon | Coming soon |
| OfficeQA Pro | 67.7% | 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 Opus 5.5 public-lane score: 81.8 (Estimated · #4/189)
- Grok 4.20 public-lane score: 50.5 (Supported · #87/189)

| Benchmark | Claude Opus 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| HLE w/o tools | 64.4% | 31.6% | Claude Opus 5.5 |
| HealthBench (raw) | 68.1% | Coming soon | Coming soon |
| HealthBench (length-adjusted) | 60.6% | Coming soon | Coming soon |
| HealthBench Professional | 65.6% | Coming soon | Coming soon |
| HealthBench Professional (raw) | 77.1% | Coming soon | Coming soon |
| BioMysteryBench (human-solvable) | 89.3% | Coming soon | Coming soon |
| BioMysteryBench (human-difficult) | 50.0% | Coming soon | Coming soon |
| SpatialBench Verified | 72.0% | Coming soon | Coming soon |
| SingleCellBench | 61.2% | Coming soon | Coming soon |
| Morphology-to-molecule matching | 34.0% | Coming soon | Coming soon |
| Medicinal chemistry | 63.5% | Coming soon | Coming soon |
| Protein Design | 60.2% | Coming soon | Coming soon |
| Protein Design library ranking | 56.0% | Coming soon | Coming soon |
| De novo protein-binder design | 82.6% | Coming soon | Coming soon |
| Protocols (troubleshooting) | 73.7% | Coming soon | Coming soon |
| Protocols (understanding) | 69.0% | Coming soon | Coming soon |
| 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 Opus 5.5 public-lane score: Coming soon
- Grok 4.20 public-lane score: Coming soon

| Benchmark | Claude Opus 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| GMMLU | 94.3% | Coming soon | Coming soon |
| MILU | 93.1% | Coming soon | Coming soon |

### Mathematics

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

| Benchmark | Claude Opus 5.5 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| ArXivMath Aug. 2026 (no tools) | 91.2% | Coming soon | Coming soon |
| ArXivMath Aug. 2026 (tools) | 96.9% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Opus 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 Opus 5.5 vs Grok 4.20 Multi-agent](/compare/claude-opus-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 Opus 5.5 vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-claude-opus-5-5)
- [Grok 4.20 vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-grok-4-20-beta)

## Explore More

- [Claude Opus 5.5 profile](/models/claude-opus-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)