# Claude Sonnet 5 vs GPT-5.5

> Side-by-side benchmark comparison for Claude Sonnet 5 and GPT-5.5 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-sonnet-5-vs-gpt-5-5
- Last updated: September 29, 2026

- Shared sourced benchmarks: 13
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Pick GPT-5.5 if you want the stronger benchmark profile. Claude Sonnet 5 only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- GPT-5.5 leads overall 69.04 to 66.99.
- The clearest category separation is in reasoning, where the averages are 78.7 for Claude Sonnet 5 and 66.1 for GPT-5.5.
- The biggest single benchmark swing is HLE in Knowledge, with scores of 57.4% and 52.2%.
- Claude Sonnet 5 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Claude Sonnet 5 | GPT-5.5 |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Overall Score | 66.99 | 69.04 |
| Benchmarks Covered | 26 | 39 |
| Pricing (input/output) | $2.00 / $10.00 | $5.00 / $30.00 |

## Category Breakdown

### Agentic

- Winner: Claude Sonnet 5
- Claude Sonnet 5 public-lane score: 64.6 (Supported · #12/117)
- GPT-5.5 public-lane score: 60.1 (Supported · #19/117)

| Benchmark | Claude Sonnet 5 | GPT-5.5 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 3.0 | 14.6% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 80.4% | Coming soon | Coming soon |
| BrowseComp | 84.7% | 84.4% | Claude Sonnet 5 |
| HLE w/ tools | 57.4% | Coming soon | Coming soon |
| OSWorld-Verified | 81.2% | 78.7% | Claude Sonnet 5 |
| Terminal-Bench 2.1 (Vals) | 74.5% | 76.4% | GPT-5.5 |
| ApprenticeBench | 16% | 20% | GPT-5.5 |
| Terminal-Bench 2.0 | Coming soon | 82% | Coming soon |
| CyberGym | Coming soon | 81.8% | Coming soon |
| MCP Atlas | Coming soon | 75.3% | Coming soon |
| Toolathlon | Coming soon | 55.6% | Coming soon |
| τ²-bench results | Coming soon | 98% | Coming soon |
| Gert Labs | Coming soon | 72.93% | Coming soon |
| ResearchClawBench | Coming soon | 17.0% | Coming soon |
| OSWorld 2.0 | Coming soon | 13.0% | Coming soon |
| JobBench | Coming soon | 42.7% | Coming soon |
| ExploitGym | Coming soon | 13.4% | Coming soon |

### Coding

- Winner: GPT-5.5
- Claude Sonnet 5 public-lane score: 59.8 (Supported · #19/142)
- GPT-5.5 public-lane score: 62.7 (Supported · #12/142)

| Benchmark | Claude Sonnet 5 | GPT-5.5 | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 85.2% | Coming soon | Coming soon |
| SWE-bench Pro | 63.2% | 58.6% | Claude Sonnet 5 |
| SWE Multilingual | 78.3% | Coming soon | Coming soon |
| SWE Multimodal | 28.1% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 80.4% | Coming soon | Coming soon |
| FrontierCode 1.1 Main | 42.7% | 43.0% | GPT-5.5 |
| cursorBench32 | 61.5% | 58.4% | Claude Sonnet 5 |
| VulcanBench CII v1 | 89.2% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 82.4% | 85.3% | GPT-5.5 |
| SWE-bench (Vals) | 79.6% | 82.6% | GPT-5.5 |
| cursorBench40 | 34.1% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 82.0% | Coming soon |
| Vibe Code Bench | Coming soon | 69.85% | Coming soon |
| React Native Evals | Coming soon | 84.7% | Coming soon |
| cursorBench31 | Coming soon | 59.2% | Coming soon |

### Reasoning

- Winner: Not comparable
- Claude Sonnet 5 public-lane score: 78.7 (Unranked · 2 rankable rows)
- GPT-5.5 public-lane score: 66.1 (#16/27)

| Benchmark | Claude Sonnet 5 | GPT-5.5 | Winner |
|-----------|-----------|-----------|--------|
| MRCR v2 64K-128K | Coming soon | 83.1% | Coming soon |
| MRCR v2 128K-256K | Coming soon | 87.5% | Coming soon |
| ARC-AGI-2 | Coming soon | 85% | Coming soon |
| ARC-AGI-3 | Coming soon | 0.4% | Coming soon |

### Multimodal & Grounded

- Winner: Directional only
- Claude Sonnet 5 public-lane score: 78.4 (#15/50)
- GPT-5.5 public-lane score: 71.4 (#20/50)

| Benchmark | Claude Sonnet 5 | GPT-5.5 | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | 88.3% | Coming soon | Coming soon |
| CharXiv w/o tools | 77% | Coming soon | Coming soon |
| MMMU-Pro | Coming soon | 81.2% | Coming soon |
| MMMU-Pro w/ Python | Coming soon | 83.2% | Coming soon |
| OfficeQA Pro | Coming soon | 54.1% | Coming soon |

### Knowledge

- Winner: GPT-5.5
- Claude Sonnet 5 public-lane score: 64.5 (Supported · #26/168)
- GPT-5.5 public-lane score: 69.8 (Supported · #13/168)

| Benchmark | Claude Sonnet 5 | GPT-5.5 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 57.4% | 52.2% | Claude Sonnet 5 |
| HLE w/o tools | 43.2% | 41.4% | Claude Sonnet 5 |
| HLE-Verified | 31.0% | Coming soon | Coming soon |
| LABBench2 | 80.1% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 88.9% | 93.2% | GPT-5.5 |
| MMLU-Pro (Vals) | 87.5% | 88.1% | GPT-5.5 |
| GPQA | Coming soon | 93.6% | Coming soon |
| GPQA-D | Coming soon | 93.6% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Claude Sonnet 5 public-lane score: Coming soon
- GPT-5.5 public-lane score: 91.9 (#7/124)

### Mathematics

- Winner: Not comparable
- Claude Sonnet 5 public-lane score: Coming soon
- GPT-5.5 public-lane score: 69.4 (Unranked · 3 rankable rows)

| Benchmark | Claude Sonnet 5 | GPT-5.5 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | Coming soon | 51.7% | Coming soon |
| FrontierMath v2 (Tiers 1-3) | Coming soon | 51.700% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 35.400% | Coming soon |

## FAQ

### Which is better overall, Claude Sonnet 5 or GPT-5.5?

GPT-5.5 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Sonnet 5 and GPT-5.5?

The widest category gap is in reasoning, where the averages are 78.7 for Claude Sonnet 5 and 66.1 for GPT-5.5.

### How many benchmarks does Claude Sonnet 5 cover on BenchLM?

Claude Sonnet 5 currently has 26 sourced benchmark scores on BenchLM.

### How many benchmarks does GPT-5.5 cover on BenchLM?

GPT-5.5 currently has 39 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Sonnet 5 vs GPT-5.5 Pro](/compare/claude-sonnet-5-vs-gpt-5-5-pro)
- [GPT-5.5 vs GPT-5.5 Pro](/compare/gpt-5-5-vs-gpt-5-5-pro)
- [Claude Sonnet 5 vs GPT-6 Astra](/compare/claude-sonnet-5-vs-gpt-6-astra)
- [GPT-5.5 vs GPT-6 Astra](/compare/gpt-5-5-vs-gpt-6-astra)

## Explore More

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