# Claude Opus 4.8 vs GPT-OSS 120B

> Side-by-side benchmark comparison for Claude Opus 4.8 and GPT-OSS 120B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-opus-4-8-vs-gpt-oss-120b
- Last updated: October 10, 2026

- Shared sourced benchmarks: 4
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Pick Claude Opus 4.8 if you want the stronger benchmark profile. GPT-OSS 120B only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Claude Opus 4.8 leads overall 69.12 to 37.22.
- The clearest category separation is in agentic, where the averages are 61.6 for Claude Opus 4.8 and 18.7 for GPT-OSS 120B.
- The biggest single benchmark swing is Gert Labs in Agentic, with scores of 72.97% and 29.61%.
- GPT-OSS 120B is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Claude Opus 4.8 also has the larger context window at 1M.

## Model Snapshot

| Property | Claude Opus 4.8 | GPT-OSS 120B |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 1M | 128K |
| Overall Score | 69.12 | 37.22 |
| Benchmarks Covered | 40 | 8 |
| Pricing (input/output) | $5.00 / $25.00 | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Directional only
- Claude Opus 4.8 public-lane score: 61.6 (Supported · #20/123)
- GPT-OSS 120B public-lane score: 18.7 (Estimated · #104/123)

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 3.0 | 21.1% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 74.6% | Coming soon | Coming soon |
| BrowseComp | 84.3% | Coming soon | Coming soon |
| DeepSearchQA | 93.1% | Coming soon | Coming soon |
| OSWorld-Verified | 83.4% | Coming soon | Coming soon |
| Finance Agent v2 | 53.9% | Coming soon | Coming soon |
| MCP Atlas | 82.2% | Coming soon | Coming soon |
| Toolathlon | 59.9% | Coming soon | Coming soon |
| Gert Labs | 72.97% | 29.61% | Claude Opus 4.8 |
| ResearchClawBench | 21.1% | Coming soon | Coming soon |
| OSWorld 2.0 | 20.6% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 71.9% | Coming soon | Coming soon |

### Coding

- Winner: Directional only
- Claude Opus 4.8 public-lane score: 60.8 (Supported · #19/146)
- GPT-OSS 120B public-lane score: 23.8 (Estimated · #107/146)

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 88.6% | 62.4% | Claude Opus 4.8 |
| SWE-bench Pro | 69.2% | Coming soon | Coming soon |
| SWE Multilingual | 84.4% | Coming soon | Coming soon |
| SWE Multimodal | 38.4% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 74.6% | Coming soon | Coming soon |
| cursorBench31 | 58.4% | Coming soon | Coming soon |
| CursorBench 3.2 | 62.3% | Coming soon | Coming soon |
| FrontierCode 1.1 Main | 46.5% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 87.8% | Coming soon | Coming soon |
| SWE-bench (Vals) | 88.6% | Coming soon | Coming soon |
| PostTrainBench v1.1 | 32.9% | Coming soon | Coming soon |
| React Native Evals | Coming soon | 71.6% | Coming soon |

### Reasoning

- Winner: Not comparable
- Claude Opus 4.8 public-lane score: 62.9 (#24/28)
- GPT-OSS 120B public-lane score: 61.7 (Unranked · 2 rankable rows)

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | 72.1% | Coming soon | Coming soon |
| ARC-AGI-3 | 1.5% | Coming soon | Coming soon |
| ARC-AGI-1 | 92.50% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Opus 4.8 public-lane score: 91.2 (#5/54)
- GPT-OSS 120B public-lane score: Coming soon

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| OfficeQA Pro | 66.2% | Coming soon | Coming soon |
| ScreenSpot Pro | 87.9% | Coming soon | Coming soon |
| CharXiv | 89.9% | Coming soon | Coming soon |
| CharXiv w/o tools | 80.5% | Coming soon | Coming soon |

### Knowledge

- Winner: Claude Opus 4.8
- Claude Opus 4.8 public-lane score: 70.7 (Supported · #14/177)
- GPT-OSS 120B public-lane score: 38.6 (Supported · #115/177)

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 93.6% | 80.1% | Claude Opus 4.8 |
| GPQA-D | 93.6% | Coming soon | Coming soon |
| HLE | 57.9% | 14.9% | Claude Opus 4.8 |
| HLE w/o tools | 49.8% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 92.4% | Coming soon | Coming soon |
| MMLU-Pro (Vals) | 89.6% | Coming soon | Coming soon |
| MMLU | Coming soon | 90% | Coming soon |

### Multilingual

- Winner: Not comparable
- Claude Opus 4.8 public-lane score: Coming soon
- GPT-OSS 120B public-lane score: Coming soon

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| INCLUDE | 87.6% | Coming soon | Coming soon |

### Instruction Following

- Winner: Directional only
- Claude Opus 4.8 public-lane score: 75.4 (#61/127)
- GPT-OSS 120B public-lane score: 84.3 (#48/127)

### Mathematics

- Winner: Not comparable
- Claude Opus 4.8 public-lane score: 65.7 (#2/7)
- GPT-OSS 120B public-lane score: Coming soon

| Benchmark | Claude Opus 4.8 | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| USAMO 2026 | 96.7% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 47.241% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 31.250% | Coming soon | Coming soon |
| AIME 2024 | Coming soon | 95.8% | Coming soon |
| AIME 2025 | Coming soon | 92.5% | Coming soon |

## FAQ

### Which is better overall, Claude Opus 4.8 or GPT-OSS 120B?

Claude Opus 4.8 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Opus 4.8 and GPT-OSS 120B?

The widest category gap is in agentic, where the averages are 61.6 for Claude Opus 4.8 and 18.7 for GPT-OSS 120B.

### How many benchmarks does Claude Opus 4.8 cover on BenchLM?

Claude Opus 4.8 currently has 40 sourced benchmark scores on BenchLM.

### How many benchmarks does GPT-OSS 120B cover on BenchLM?

GPT-OSS 120B currently has 8 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Opus 4.8 vs GPT-OSS 20B](/compare/claude-opus-4-8-vs-gpt-oss-20b)
- [GPT-OSS 120B vs GPT-OSS 20B](/compare/gpt-oss-120b-vs-gpt-oss-20b)
- [Claude Opus 4.8 vs Claude Opus 5.5](/compare/claude-opus-4-8-vs-claude-opus-5-5)
- [GPT-OSS 120B vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-oss-120b)

## Explore More

- [Claude Opus 4.8 profile](/models/claude-opus-4-8)
- [GPT-OSS 120B profile](/models/gpt-oss-120b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)