# gpt-oss-20b vs Mercury

> Mercury is the stronger model overall, scoring 37.3 to 32.1 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-oss-20b-vs-mercury
- Last updated: 2026-10-10
- Shared benchmarks: 9

## Summary

- They share 9 benchmarks with published results for both. gpt-oss-20b scores higher in 2 categories and Mercury in 4 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Mercury leads 46.2 to 35.8.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 53.2% for gpt-oss-20b and 21.6% for Mercury.
- gpt-oss-20b has downloadable open weights; the other is API-only.

## Snapshot

| | gpt-oss-20b | Mercury |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 32.1 | 37.3 |
| Rank | 249 | 192 |
| Context | 131K | — |
| Input $/M | $0.018 | — |
| Output $/M | $0.09 | — |
| Weights | Open | Proprietary |

## Coding

- gpt-oss-20b: 37.1 (#185)
- Mercury: 38.1 (#164)

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| LMArena Coding | 1307 | 1323 |
| SciCode | 34.4% | — |
| WeirdML | 40.9% | — |
| ALE-Bench | 566.05 | — |

## Agentic & Tool Use

- gpt-oss-20b: 9.2 (#146)
- Mercury: —

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| Terminal-Bench | 3.4% | — |

## Reasoning

- gpt-oss-20b: 18.8 (#251)
- Mercury: 16.8 (#288)

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| Kagi LLM Benchmark | 53.2% | 21.6% |
| LMArena Hard Prompts | 1274 | 1284 |
| CritPt | 1.4% | — |
| Chess Puzzles | 4% | — |
| DTBench | 68% | — |
| LMCA | 14.5% | — |
| Epoch Capabilities Index | 137.81 | — |

## Math

- gpt-oss-20b: 37.6 (#93)
- Mercury: —

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 65.3% | — |
| Omni-MATH | 56.5% | — |
| LMArena Math | 1317 | — |

## Knowledge

- gpt-oss-20b: 34.6 (#186)
- Mercury: —

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| GPQA Diamond | 60.8% | — |
| MMLU-Pro | 74% | — |
| GPQA (HELM) | 59.4% | — |
| LMArena Expert | 1258 | — |

## Multilingual

- gpt-oss-20b: 42.4 (#192)
- Mercury: 41.7 (#201)

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| LMArena Non-English | 1269 | 1259 |
| LMArena Chinese | 1311 | — |
| LMArena German | 1249 | — |
| LMArena Japanese | 1245 | — |
| LMArena Korean | 1239 | — |
| LMArena Russian | 1279 | — |
| LMArena Spanish | 1267 | — |

## Instruction Following

- gpt-oss-20b: 62.0 (#235)
- Mercury: 65.3 (#220)

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| LMArena Instruction Following | 1236 | 1238 |
| IFEval | 73.2% | — |

## Long Context

- gpt-oss-20b: 37.9 (#203)
- Mercury: 38.3 (#193)

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| LMArena Longer Query | 1251 | 1264 |

## Writing & Preference

- gpt-oss-20b: 35.8 (#260)
- Mercury: 46.2 (#216)

| Benchmark | gpt-oss-20b | Mercury |
|---|---|---|
| LMArena Text | 1288 | 1282 |
| LMArena Creative Writing | 1201 | 1186 |
| LMArena Multi-Turn | 1268 | 1283 |
| EQ-Bench Creative Writing | 666 | — |
| WildBench | 73.7% | — |

## FAQ

### Is gpt-oss-20b better than Mercury?

Mercury is the stronger model overall, scoring 37.3 to 32.1 on the Noometry Index.

### Is gpt-oss-20b or Mercury better for coding?

They score almost the same on coding (37.1 vs 38.1); test both on your own repository before choosing.

### How many benchmarks do gpt-oss-20b and Mercury share?

9 benchmarks have published results for both models. gpt-oss-20b has 34 scored results on Noometry and Mercury has 9.