# GPT-5.2-Codex vs GPT-OSS 120B

> Side-by-side benchmark comparison for GPT-5.2-Codex and GPT-OSS 120B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-2-codex-vs-gpt-oss-120b
- Last updated: October 17, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.2-Codex and GPT-OSS 120B share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- GPT-OSS 120B has the lower published output-token price.
- GPT-5.2-Codex has the larger published context window at 400K.

## Model Snapshot

| Property | GPT-5.2-Codex | GPT-OSS 120B |
|----------|----------|----------|
| Creator | OpenAI | OpenAI |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 400K | 128K |
| Independent public score (not head-to-head) | 55.3 | 37.32 |
| Benchmarks Covered | 5 | 8 |
| Pricing (input/output) | $1.75 / $14.00 | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: 40.8 (Estimated · #64/128)
- GPT-OSS 120B public-lane score: 19.5 (Estimated · #110/128)

| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | 51.79% | 29.61% | GPT-5.2-Codex |
| JobBench | 26.0% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: 43.7 (Supported · #56/150)
- GPT-OSS 120B public-lane score: 23 (Estimated · #111/150)

| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | 37.91% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 88.0% | Coming soon | Coming soon |
| SWE-bench (Vals) | 72.4% | Coming soon | Coming soon |
| SWE-bench Verified | Coming soon | 62.4% | Coming soon |
| React Native Evals | Coming soon | 71.6% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: 82.4 (Unranked · 2 rankable rows)
- GPT-OSS 120B public-lane score: 61.6 (Unranked · 2 rankable rows)

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: 76.9 (Unranked · 1 rankable row)
- GPT-OSS 120B public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: 56.4 (Estimated · #54/184)
- GPT-OSS 120B public-lane score: 38.6 (Supported · #122/184)

| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| MMLU | Coming soon | 90% | Coming soon |
| GPQA | Coming soon | 80.1% | Coming soon |
| HLE | Coming soon | 14.9% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: 93.8 (#4/148)
- GPT-OSS 120B public-lane score: 84.3 (#50/148)

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.2-Codex public-lane score: Coming soon
- GPT-OSS 120B public-lane score: Coming soon

| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Winner |
|-----------|-----------|-----------|--------|
| AIME 2024 | Coming soon | 95.8% | Coming soon |
| AIME 2025 | Coming soon | 92.5% | Coming soon |

## FAQ

### Is there enough evidence to pick between GPT-5.2-Codex and GPT-OSS 120B?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [GPT-5.2-Codex vs GPT-OSS 20B](/compare/gpt-5-2-codex-vs-gpt-oss-20b)
- [GPT-OSS 120B vs GPT-OSS 20B](/compare/gpt-oss-120b-vs-gpt-oss-20b)
- [GPT-5.2-Codex vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-5-2-codex)
- [GPT-OSS 120B vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-oss-120b)

## Explore More

- [GPT-5.2-Codex profile](/models/gpt-5-2-codex)
- [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)