# Claude Sonnet 5.5 vs GPT-6 Luna

> Side-by-side benchmark comparison for Claude Sonnet 5.5 and GPT-6 Luna across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-sonnet-5-5-vs-gpt-6-luna
- Last updated: September 28, 2026

- Shared sourced benchmarks: 5
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Pick Claude Sonnet 5.5 if you want the stronger benchmark profile. GPT-6 Luna only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Claude Sonnet 5.5 leads overall 80.49 to 66.45.
- The clearest category separation is in coding, where the averages are 79.6 for Claude Sonnet 5.5 and 51.1 for GPT-6 Luna.
- The biggest single benchmark swing is HealthBench (raw) in Knowledge, with scores of 69.4% and 50.0%.
- GPT-6 Luna is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- GPT-6 Luna also has the larger context window at 1.05M.

## Model Snapshot

| Property | Claude Sonnet 5.5 | GPT-6 Luna |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1.05M |
| Overall Score | 80.49 | 66.45 |
| Benchmarks Covered | 47 | 10 |
| Pricing (input/output) | $2.00 / $10.00 | $0.10 / $0.50 |

## Category Breakdown

### Agentic

- Winner: Directional only
- Claude Sonnet 5.5 public-lane score: 66.1 (Supported · #10/111)
- GPT-6 Luna public-lane score: 55.5 (Estimated · #29/111)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | 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 |
| ExploitGym | Coming soon | 11.6% | Coming soon |

### Coding

- Winner: Directional only
- Claude Sonnet 5.5 public-lane score: 79.6 (Estimated · #3/136)
- GPT-6 Luna public-lane score: 51.1 (Supported · #35/136)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| FrontierCode 1.1 Main | 46.2% | Coming soon | Coming soon |
| cursorBench40 | 55.5% | Coming soon | Coming soon |
| SWE-bench Pro | 81.3% | Coming soon | Coming soon |
| SWE Multilingual | 90.3% | Coming soon | Coming soon |
| SWE Multimodal | 54.3% | Coming soon | Coming soon |
| DeepSWE | 71.0% | 66.6% | Claude Sonnet 5.5 |
| 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 |

### Reasoning

- Winner: Directional only
- Claude Sonnet 5.5 public-lane score: 79.2 (#7/27)
- GPT-6 Luna public-lane score: 55.6 (#25/27)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | Coming soon | 86.70% | Coming soon |
| ARC-AGI-2 | Coming soon | 59.3% | Coming soon |
| ARC-AGI-3 | Coming soon | 0.1% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Sonnet 5.5 public-lane score: 83.3 (Unranked · 7 rankable rows)
- GPT-6 Luna public-lane score: 72.3 (Unranked · 1 rankable row)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | 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 |

### Knowledge

- Winner: Claude Sonnet 5.5
- Claude Sonnet 5.5 public-lane score: 80.9 (Supported · #6/160)
- GPT-6 Luna public-lane score: 65.3 (Supported · #21/160)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| HealthBench (raw) | 69.4% | 50.0% | Claude Sonnet 5.5 |
| HealthBench (length-adjusted) | 65.4% | 54.5% | Claude Sonnet 5.5 |
| HealthBench Professional (raw) | 77.1% | 61.2% | Claude Sonnet 5.5 |
| HealthBench Professional | 69.2% | 60.8% | Claude Sonnet 5.5 |
| 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% | Coming soon | Coming soon |
| HealthBench Hard | Coming soon | 31.4% | Coming soon |

### Multilingual

- Winner: Not comparable
- Claude Sonnet 5.5 public-lane score: Coming soon
- GPT-6 Luna public-lane score: Coming soon

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| GMMLU | 92.1% | Coming soon | Coming soon |
| MILU | 91.6% | Coming soon | Coming soon |

### Mathematics

- Winner: Not comparable
- Claude Sonnet 5.5 public-lane score: Coming soon
- GPT-6 Luna public-lane score: Coming soon

| Benchmark | Claude Sonnet 5.5 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| ArXivMath Aug. 2026 (no tools) | 86.8% | Coming soon | Coming soon |
| ArXivMath Aug. 2026 (tools) | 95.2% | Coming soon | Coming soon |

## FAQ

### Which is better overall, Claude Sonnet 5.5 or GPT-6 Luna?

Claude Sonnet 5.5 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Sonnet 5.5 and GPT-6 Luna?

The widest category gap is in coding, where the averages are 79.6 for Claude Sonnet 5.5 and 51.1 for GPT-6 Luna.

### How many benchmarks does Claude Sonnet 5.5 cover on BenchLM?

Claude Sonnet 5.5 currently has 47 sourced benchmark scores on BenchLM.

### How many benchmarks does GPT-6 Luna cover on BenchLM?

GPT-6 Luna currently has 10 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Sonnet 5.5 vs GPT-6 Astra](/compare/claude-sonnet-5-5-vs-gpt-6-astra)
- [GPT-6 Luna vs GPT-6 Astra](/compare/gpt-6-astra-vs-gpt-6-luna)
- [Claude Sonnet 5.5 vs GPT-6 Sol](/compare/claude-sonnet-5-5-vs-gpt-6-sol)
- [GPT-6 Luna vs GPT-6 Sol](/compare/gpt-6-luna-vs-gpt-6-sol)

## Explore More

- [Claude Sonnet 5.5 profile](/models/claude-sonnet-5-5)
- [GPT-6 Luna profile](/models/gpt-6-luna)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)