# Claude Sonnet 5.5 vs GPT-6 Astra

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

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

- Shared sourced benchmarks: 12
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

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

## Summary

- GPT-6 Astra leads overall 88.5 to 80.49.
- The clearest category separation is in reasoning, where the averages are 79.2 for Claude Sonnet 5.5 and 89.6 for GPT-6 Astra.
- The biggest single benchmark swing is Terminal-Bench 4.0 in Agentic, with scores of 70.60% and 57.90%.
- Claude Sonnet 5.5 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- GPT-6 Astra also has the larger context window at 1.05M.

## Model Snapshot

| Property | Claude Sonnet 5.5 | GPT-6 Astra |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1.05M |
| Overall Score | 80.49 | 88.5 |
| Benchmarks Covered | 47 | 30 |
| Pricing (input/output) | $2.00 / $10.00 | $10.00 / $50.00 |

## Category Breakdown

### Agentic

- Winner: GPT-6 Astra
- Claude Sonnet 5.5 public-lane score: 66.1 (Supported · #10/111)
- GPT-6 Astra public-lane score: 70.7 (Supported · #5/111)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 70.60% | 57.90% | Claude Sonnet 5.5 |
| HLE w/ tools | 64.5% | 57.2% | Claude Sonnet 5.5 |
| DRACO | 87.0% | Coming soon | Coming soon |
| Terminal-Bench-Science 0.1 | 59.9% | 64.6% | GPT-6 Astra |
| 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 |
| BrowseComp | Coming soon | 91.5% | Coming soon |
| OSWorld 2.0 | Coming soon | 72.6% | Coming soon |
| ExploitGym | Coming soon | 42.4% | Coming soon |
| Agents' Last Exam | Coming soon | 59.3% | Coming soon |
| AutomationBench | Coming soon | 41.4% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 87.3% | Coming soon |
| ApprenticeBench | Coming soon | 68% | Coming soon |

### Coding

- Winner: Directional only
- Claude Sonnet 5.5 public-lane score: 79.6 (Estimated · #3/136)
- GPT-6 Astra public-lane score: 74 (Supported · #4/136)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | Winner |
|-----------|-----------|-----------|--------|
| FrontierCode 1.1 Main | 46.2% | 53.3% | GPT-6 Astra |
| 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% | 74.1% | GPT-6 Astra |
| FrontierCode 1.1 Extended | 59.1% | 64.5% | GPT-6 Astra |
| ProgramBench | 79.7% | Coming soon | Coming soon |
| FrontierSWE v2 | 61.9% | 65.5% | GPT-6 Astra |

### Reasoning

- Winner: Directional only
- Claude Sonnet 5.5 public-lane score: 79.2 (#7/27)
- GPT-6 Astra public-lane score: 89.6 (#1/27)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | Coming soon | 98.50% | Coming soon |
| ARC-AGI-2 | Coming soon | 95% | Coming soon |
| ARC-AGI-3 | Coming soon | 62.7% | Coming soon |
| GeneBench-Pro | Coming soon | 37.8% | Coming soon |
| MRCR v2 256K-512K | Coming soon | 100.0% | Coming soon |
| MRCR v2 512K-1M | Coming soon | 96.3% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Sonnet 5.5 public-lane score: 83.3 (Unranked · 7 rankable rows)
- GPT-6 Astra public-lane score: 83.9 (Unranked · 3 rankable rows)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | 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 | 0.959 | Claude Sonnet 5.5 |
| Biomedical image analysis | 72.2% | Coming soon | Coming soon |
| OfficeQA | 76.9% | Coming soon | Coming soon |
| OfficeQA Pro | 65.6% | Coming soon | Coming soon |
| ScreenSpot Pro | Coming soon | 92.7% | Coming soon |

### Knowledge

- Winner: GPT-6 Astra
- Claude Sonnet 5.5 public-lane score: 80.9 (Supported · #6/160)
- GPT-6 Astra public-lane score: 86.8 (Supported · #2/160)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | Winner |
|-----------|-----------|-----------|--------|
| HealthBench (raw) | 69.4% | 56.9% | Claude Sonnet 5.5 |
| HealthBench (length-adjusted) | 65.4% | 58.3% | Claude Sonnet 5.5 |
| HealthBench Professional (raw) | 77.1% | 68.2% | Claude Sonnet 5.5 |
| HealthBench Professional | 69.2% | 64.7% | 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 |
| GPQA | Coming soon | 96% | Coming soon |
| GPQA-D | Coming soon | 96.0% | Coming soon |
| HealthBench Hard | Coming soon | 36.6% | Coming soon |

### Multilingual

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

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | 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 Astra public-lane score: 85 (Unranked · 1 rankable row)

| Benchmark | Claude Sonnet 5.5 | GPT-6 Astra | Winner |
|-----------|-----------|-----------|--------|
| ArXivMath Aug. 2026 (no tools) | 86.8% | Coming soon | Coming soon |
| ArXivMath Aug. 2026 (tools) | 95.2% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 97.600% | Coming soon |

## FAQ

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

GPT-6 Astra is ahead overall on BenchLM right now.

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

The widest category gap is in reasoning, where the averages are 79.2 for Claude Sonnet 5.5 and 89.6 for GPT-6 Astra.

### 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 Astra cover on BenchLM?

GPT-6 Astra currently has 30 sourced benchmark scores on BenchLM.

## Related Comparisons

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

## Explore More

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