# GPT-5 Pro vs gpt-oss-120b

> GPT-5 Pro is the stronger model overall, scoring 46.4 to 36.3 on the Noometry Index. gpt-oss-120b costs 587× less per token, which makes it the better buy when GPT-5 Pro's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-5-pro-vs-gpt-oss-120b
- Last updated: 2026-10-12
- Shared benchmarks: 5

## Summary

- They share 5 benchmarks with published results for both. GPT-5 Pro scores higher in 3 categories and gpt-oss-120b in 1 category; 4 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5 Pro leads 38.9 to 20.0.
- The biggest single-benchmark swing is SimpleBench: 61.6% for GPT-5 Pro and 22.1% for gpt-oss-120b.
- gpt-oss-120b is cheaper at $0.037 / $0.17 per million input/output tokens, against $15 / $120 for GPT-5 Pro.
- GPT-5 Pro accepts more context: 400K tokens versus 131K.
- gpt-oss-120b has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 46.4 | 36.3 |
| Rank | 64 | 217 |
| Context | 400K | 131K |
| Input $/M | $15 | $0.037 |
| Output $/M | $120 | $0.17 |
| Weights | Proprietary | Open |

## Coding

- GPT-5 Pro: 44.0 (#80)
- gpt-oss-120b: 33.5 (#256)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| WeirdML | 60.4% | 48.2% |
| AlgoTune | 1.31 | 1.41 |
| SWE-bench Verified (bash only) | — | 26% |
| Aider Polyglot | — | 41.8% |
| SciCode | — | 36% |
| LMArena Coding | — | 1380 |
| ALE-Bench | — | 575.62 |

## Agentic & Tool Use

- GPT-5 Pro: —
- gpt-oss-120b: 12.2 (#153)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| Terminal-Bench | — | 18.7% |
| APEX-Agents | — | 4.4% |
| METR Time Horizons | — | 56.6% |
| Vending-Bench 2 | — | -21.53 |

## Reasoning

- GPT-5 Pro: 38.9 (#62)
- gpt-oss-120b: 20.0 (#245)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| SimpleBench | 61.6% | 22.1% |
| Kagi LLM Benchmark | 76.8% | 58.6% |
| Epoch Capabilities Index | 150.28 | 139.93 |
| ARC-AGI-2 | 18.3% | — |
| ARC-AGI-1 | 70.2% | — |
| CritPt | — | 1.1% |
| Chess Puzzles | — | 20% |
| EnigmaEval | 18.8% | — |
| LMArena Hard Prompts | — | 1364 |
| Mystery Game Puzzles | — | 2% |
| DTBench | — | 76.3% |
| LMCA | — | 22.1% |
| Surface Evolver Bench | — | 25% |

## Math

- GPT-5 Pro: 48.5 (#63)
- gpt-oss-120b: 52.5 (#50)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| FrontierMath (Tiers 1-3) | 55.8% | — |
| FrontierMath Tier 4 | 19.5% | — |
| OTIS Mock AIME 2024-2025 | — | 88.9% |
| Omni-MATH | — | 68.8% |
| LMArena Math | — | 1389 |
| FrontierMath Tier 4 (v1) | 14.6% | — |

## Knowledge

- GPT-5 Pro: 56.7 (#42)
- gpt-oss-120b: 42.4 (#96)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| GPQA Diamond | — | 75.8% |
| Humanity's Last Exam | 31.6% | — |
| MMLU-Pro | — | 79.5% |
| Confabulations | — | 15.7% |
| Vectara Hallucination Rate | — | 14.2% |
| GPQA (HELM) | — | 68.4% |
| LMArena Expert | — | 1356 |

## Multilingual

- GPT-5 Pro: —
- gpt-oss-120b: 48.0 (#147)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| LMArena Non-English | — | 1351 |
| LMArena Chinese | — | 1385 |
| LMArena French | — | 1369 |
| LMArena German | — | 1353 |
| LMArena Japanese | — | 1331 |
| LMArena Korean | — | 1282 |
| LMArena Russian | — | 1343 |
| LMArena Spanish | — | 1389 |

## Instruction Following

- GPT-5 Pro: —
- gpt-oss-120b: 69.3 (#173)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| IFEval | — | 83.6% |
| LMArena Instruction Following | — | 1318 |

## Long Context

- GPT-5 Pro: —
- gpt-oss-120b: 31.4 (#278)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| Fiction.LiveBench | — | 44.4% |
| LMArena Longer Query | — | 1319 |

## Writing & Preference

- GPT-5 Pro: —
- gpt-oss-120b: 46.5 (#217)

| Benchmark | GPT-5 Pro | gpt-oss-120b |
|---|---|---|
| LMArena Text | — | 1365 |
| LMArena Creative Writing | — | 1275 |
| Short-Story Creative Writing | — | 77.1% |
| EQ-Bench Creative Writing | — | 961 |
| WildBench | — | 84.5% |
| LMArena Multi-Turn | — | 1340 |

## FAQ

### Is GPT-5 Pro better than gpt-oss-120b?

GPT-5 Pro is the stronger model overall, scoring 46.4 to 36.3 on the Noometry Index. gpt-oss-120b costs 587× less per token, which makes it the better buy when GPT-5 Pro's lead doesn't matter for your workload.

### Which is cheaper, GPT-5 Pro or gpt-oss-120b?

gpt-oss-120b is cheaper. It lists at $0.037 per million input tokens and $0.17 per million output tokens; GPT-5 Pro lists at $15 and $120.

### Is GPT-5 Pro or gpt-oss-120b better for coding?

GPT-5 Pro scores higher on coding benchmarks: 44.0 versus 33.5 in the Noometry coding category.

### Which has the bigger context window?

GPT-5 Pro does, with 400K tokens against 131K.

### How many benchmarks do GPT-5 Pro and gpt-oss-120b share?

5 benchmarks have published results for both models. GPT-5 Pro has 12 scored results on Noometry and gpt-oss-120b has 48.