# GPT-OSS 120B vs Kimi K2.5 (Reasoning)

> Side-by-side benchmark comparison for GPT-OSS 120B and Kimi K2.5 (Reasoning) across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-oss-120b-vs-kimi-k2-5-reasoning
- Last updated: October 17, 2026

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

## Quick Verdict

Kimi K2.5 (Reasoning) leads by point estimate. Conditional score ranges do not establish rank confidence. Choose using the category evidence and your own workload tests.

## Summary

- Kimi K2.5 (Reasoning) has the higher overall point estimate 56.09 to 37.32. Conditional score ranges do not establish rank confidence.
- The clearest category separation is in agentic, where the averages are 19.5 for GPT-OSS 120B and 38.3 for Kimi K2.5 (Reasoning).
- The biggest single benchmark swing is SWE-bench Verified in Coding, with scores of 62.4% and 76.8%.
- GPT-OSS 120B is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | GPT-OSS 120B | Kimi K2.5 (Reasoning) |
|----------|----------|----------|
| Creator | OpenAI | Moonshot AI |
| Type | Open Weight | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 128K | 128K |
| Overall Score | 37.32 | 56.09 |
| Benchmarks Covered | 8 | 15 |
| Pricing (input/output) | $0.00 / $0.00 | $0.60 / $3.00 |

## Category Breakdown

### Agentic

- Winner: Directional only
- GPT-OSS 120B public-lane score: 19.5 (Estimated · #110/128)
- Kimi K2.5 (Reasoning) public-lane score: 38.3 (Estimated · #71/128)

| Benchmark | GPT-OSS 120B | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | 29.61% | 32.58% | Kimi K2.5 (Reasoning) |
| Terminal-Bench 2.0 | Coming soon | 50.8% | Coming soon |
| BrowseComp | Coming soon | 60.6% | Coming soon |
| OSWorld-Verified | Coming soon | 63.3% | Coming soon |

### Coding

- Winner: Not comparable
- GPT-OSS 120B public-lane score: 23 (Estimated · #111/150)
- Kimi K2.5 (Reasoning) public-lane score: Coming soon

| Benchmark | GPT-OSS 120B | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 62.4% | 76.8% | Kimi K2.5 (Reasoning) |
| React Native Evals | 71.6% | Coming soon | Coming soon |
| LiveCodeBench v6 | Coming soon | 85.0% | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 50.8% | Coming soon |
| Vibe Code Bench | Coming soon | 17.54% | Coming soon |

### Reasoning

- Winner: Not comparable
- GPT-OSS 120B public-lane score: 61.6 (Unranked · 2 rankable rows)
- Kimi K2.5 (Reasoning) public-lane score: 67.1 (Unranked · 1 rankable row)

| Benchmark | GPT-OSS 120B | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | Coming soon | 61% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- GPT-OSS 120B public-lane score: Coming soon
- Kimi K2.5 (Reasoning) public-lane score: 69 (#33/54)

| Benchmark | GPT-OSS 120B | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 78.5% | Coming soon |
| CharXiv | Coming soon | 77.5% | Coming soon |

### Knowledge

- Winner: Directional only
- GPT-OSS 120B public-lane score: 38.6 (Supported · #122/184)
- Kimi K2.5 (Reasoning) public-lane score: 48.8 (Estimated · #85/184)

| Benchmark | GPT-OSS 120B | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| MMLU | 90% | Coming soon | Coming soon |
| GPQA | 80.1% | 87.6% | Kimi K2.5 (Reasoning) |
| HLE | 14.9% | Coming soon | Coming soon |
| MMLU-Pro | Coming soon | 87.1% | Coming soon |

### Instruction Following

- Winner: Not comparable
- GPT-OSS 120B public-lane score: 84.3 (#50/148)
- Kimi K2.5 (Reasoning) public-lane score: Coming soon

### Mathematics

- Winner: Not comparable
- GPT-OSS 120B public-lane score: Coming soon
- Kimi K2.5 (Reasoning) public-lane score: Coming soon

| Benchmark | GPT-OSS 120B | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| AIME 2024 | 95.8% | Coming soon | Coming soon |
| AIME 2025 | 92.5% | 96.1% | Kimi K2.5 (Reasoning) |
| HMMT Feb 2025 | Coming soon | 95.4% | Coming soon |

## FAQ

### Which is better overall, GPT-OSS 120B or Kimi K2.5 (Reasoning)?

Kimi K2.5 (Reasoning) has the higher overall point estimate. Conditional score ranges do not establish rank confidence.

### Where is the biggest gap between GPT-OSS 120B and Kimi K2.5 (Reasoning)?

The widest category gap is in agentic, where the averages are 19.5 for GPT-OSS 120B and 38.3 for Kimi K2.5 (Reasoning).

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

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

### How many benchmarks does Kimi K2.5 (Reasoning) cover on BenchLM?

Kimi K2.5 (Reasoning) currently has 15 sourced benchmark scores on BenchLM.

## Related Comparisons

- [GPT-OSS 120B vs GPT-OSS 20B](/compare/gpt-oss-120b-vs-gpt-oss-20b)
- [Kimi K2.5 (Reasoning) vs GPT-OSS 20B](/compare/gpt-oss-20b-vs-kimi-k2-5-reasoning)
- [GPT-OSS 120B vs Kimi K2.5](/compare/gpt-oss-120b-vs-kimi-k2-5)
- [Kimi K2.5 (Reasoning) vs Kimi K2.5](/compare/kimi-k2-5-vs-kimi-k2-5-reasoning)

## Explore More

- [GPT-OSS 120B profile](/models/gpt-oss-120b)
- [Kimi K2.5 (Reasoning) profile](/models/kimi-k2-5-reasoning)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)