# Claude Opus 4 vs gpt-oss-20b

> Claude Opus 4 is the stronger model overall, scoring 42.9 to 32.1 on the Noometry Index. gpt-oss-20b costs 833× less per token, which makes it the better buy when Claude Opus 4's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-opus-4-vs-gpt-oss-20b
- Last updated: 2026-10-10
- Shared benchmarks: 30

## Summary

- They share 30 benchmarks with published results for both. Claude Opus 4 scores higher in 9 categories and gpt-oss-20b in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Claude Opus 4 leads 61.4 to 35.8.
- The biggest single-benchmark swing is LMCA: 37.4% for Claude Opus 4 and 14.5% for gpt-oss-20b.
- gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $15 / $75 for Claude Opus 4.
- Claude Opus 4 accepts more context: 200K tokens versus 131K.
- gpt-oss-20b has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 42.9 | 32.1 |
| Rank | 93 | 249 |
| Context | 200K | 131K |
| Input $/M | $15 | $0.018 |
| Output $/M | $75 | $0.09 |
| Weights | Proprietary | Open |

## Coding

- Claude Opus 4: 47.8 (#55)
- gpt-oss-20b: 37.1 (#185)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| WeirdML | 43.7% | 40.9% |
| LMArena Coding | 1442 | 1307 |
| SWE-bench Verified | 70.7% | — |
| SWE-bench Verified (bash only) | 67.6% | — |
| Aider Polyglot | 72% | — |
| SciCode | — | 34.4% |
| GSO | 6.9% | — |
| ALE-Bench | — | 566.05 |
| AlgoTune | 1.33 | — |

## Agentic & Tool Use

- Claude Opus 4: 34.5 (#39)
- gpt-oss-20b: 9.2 (#146)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| Terminal-Bench | — | 3.4% |
| Cybench | 38% | — |
| DeepResearch Bench | 46.8% | — |
| LMArena Search | 1127 | — |
| METR Time Horizons | 63.9% | — |

## Reasoning

- Claude Opus 4: 27.4 (#104)
- gpt-oss-20b: 18.8 (#251)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| Kagi LLM Benchmark | 74.3% | 53.2% |
| CritPt | 0.3% | 1.4% |
| LMArena Hard Prompts | 1399 | 1274 |
| DTBench | 81.6% | 68% |
| LMCA | 37.4% | 14.5% |
| Epoch Capabilities Index | 142.67 | 137.81 |
| ARC-AGI-2 | 8.6% | — |
| SimpleBench | 58.8% | — |
| ARC-AGI-1 | 35.7% | — |
| Chess Puzzles | — | 4% |
| EnigmaEval | 5.6% | — |
| ForecastBench | 61.1 | — |

## Math

- Claude Opus 4: 40.2 (#80)
- gpt-oss-20b: 37.6 (#93)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 64.4% | 65.3% |
| Omni-MATH | 61.6% | 56.5% |
| LMArena Math | 1391 | 1317 |
| MATH Level 5 | 85% | — |
| FrontierMath (Feb 2025 set) | 4.5% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |

## Knowledge

- Claude Opus 4: 43.9 (#82)
- gpt-oss-20b: 34.6 (#186)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| GPQA Diamond | 76.3% | 60.8% |
| MMLU-Pro | 87.5% | 74% |
| GPQA (HELM) | 70.8% | 59.4% |
| LMArena Expert | 1384 | 1258 |
| Humanity's Last Exam | 10.7% | — |
| Confabulations | 15.9% | — |
| Vectara Hallucination Rate | 12% | — |

## Multimodal

- Claude Opus 4: 30.9 (#101)
- gpt-oss-20b: —

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| LMArena Vision | 1192 | — |
| GeoBench | 49% | — |
| VPCT | 38% | — |

## Multilingual

- Claude Opus 4: 49.0 (#133)
- gpt-oss-20b: 42.4 (#192)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| LMArena Non-English | 1362 | 1269 |
| LMArena Chinese | 1386 | 1311 |
| LMArena German | 1391 | 1249 |
| LMArena Japanese | 1332 | 1245 |
| LMArena Korean | 1318 | 1239 |
| LMArena Russian | 1392 | 1279 |
| LMArena Spanish | 1388 | 1267 |
| LMArena French | 1370 | — |

## Instruction Following

- Claude Opus 4: 77.3 (#26)
- gpt-oss-20b: 62.0 (#235)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| IFEval | 91.8% | 73.2% |
| LMArena Instruction Following | 1406 | 1236 |

## Long Context

- Claude Opus 4: 39.5 (#167)
- gpt-oss-20b: 37.9 (#203)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| LMArena Longer Query | 1422 | 1251 |
| Fiction.LiveBench | 61.1% | — |

## Writing & Preference

- Claude Opus 4: 61.4 (#85)
- gpt-oss-20b: 35.8 (#260)

| Benchmark | Claude Opus 4 | gpt-oss-20b |
|---|---|---|
| LMArena Text | 1377 | 1288 |
| LMArena Creative Writing | 1386 | 1201 |
| EQ-Bench Creative Writing | 1580 | 666 |
| WildBench | 85.2% | 73.7% |
| LMArena Multi-Turn | 1396 | 1268 |
| Short-Story Creative Writing | 83.6% | — |

## FAQ

### Is Claude Opus 4 better than gpt-oss-20b?

Claude Opus 4 is the stronger model overall, scoring 42.9 to 32.1 on the Noometry Index. gpt-oss-20b costs 833× less per token, which makes it the better buy when Claude Opus 4's lead doesn't matter for your workload.

### Which is cheaper, Claude Opus 4 or gpt-oss-20b?

gpt-oss-20b is cheaper. It lists at $0.018 per million input tokens and $0.09 per million output tokens; Claude Opus 4 lists at $15 and $75.

### Is Claude Opus 4 or gpt-oss-20b better for coding?

Claude Opus 4 scores higher on coding benchmarks: 47.8 versus 37.1 in the Noometry coding category.

### Which has the bigger context window?

Claude Opus 4 does, with 200K tokens against 131K.

### How many benchmarks do Claude Opus 4 and gpt-oss-20b share?

30 benchmarks have published results for both models. Claude Opus 4 has 56 scored results on Noometry and gpt-oss-20b has 34.