# gpt-oss-20b vs Step 3.5 Flash

> Step 3.5 Flash is the stronger model overall, scoring 42.3 to 32.5 on the Noometry Index. gpt-oss-20b costs 4.2× less per token, which makes it the better buy when Step 3.5 Flash's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-oss-20b-vs-step-3-5-flash
- Last updated: 2026-10-10
- Shared benchmarks: 16

## Summary

- They share 16 benchmarks with published results for both. gpt-oss-20b scores higher in 0 categories and Step 3.5 Flash in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Step 3.5 Flash leads 58.8 to 35.5.
- gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $0.10 / $0.30 for Step 3.5 Flash.
- Step 3.5 Flash accepts more context: 256K tokens versus 131K.

## Snapshot

| | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 32.5 | 42.3 |
| Rank | 255 | 116 |
| Context | 131K | 256K |
| Input $/M | $0.018 | $0.10 |
| Output $/M | $0.09 | $0.30 |
| Weights | Open | Open |

## Coding

- gpt-oss-20b: 37.6 (#192)
- Step 3.5 Flash: 42.4 (#105)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1306 | 1436 |
| SciCode | 34.4% | — |
| WeirdML | 40.9% | — |
| ALE-Bench | 566.05 | — |

## Agentic & Tool Use

- gpt-oss-20b: 9.3 (#154)
- Step 3.5 Flash: —

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| Terminal-Bench | 3.4% | — |

## Reasoning

- gpt-oss-20b: 19.3 (#261)
- Step 3.5 Flash: 22.2 (#202)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1274 | 1411 |
| Kagi LLM Benchmark | 53.2% | — |
| NYT Connections (extended) | — | 28.4% |
| CritPt | 1.4% | — |
| Chess Puzzles | 4% | — |
| DTBench | 68% | — |
| LMCA | 14.5% | — |
| Epoch Capabilities Index | 137.82 | — |

## Math

- gpt-oss-20b: 39.4 (#103)
- Step 3.5 Flash: 42.6 (#84)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1317 | 1408 |
| MathArena Final-Answer Competitions | — | 66.8% |
| OTIS Mock AIME 2024-2025 | 65.3% | — |
| Omni-MATH | 56.5% | — |

## Knowledge

- gpt-oss-20b: 34.6 (#195)
- Step 3.5 Flash: 39.6 (#132)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1258 | 1421 |
| GPQA Diamond | 60.8% | — |
| MMLU-Pro | 74% | — |
| GPQA (HELM) | 59.4% | — |

## Multilingual

- gpt-oss-20b: 42.2 (#197)
- Step 3.5 Flash: 50.5 (#119)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1268 | 1385 |
| LMArena Chinese | 1314 | 1447 |
| LMArena German | 1255 | 1405 |
| LMArena Japanese | 1244 | 1354 |
| LMArena Korean | 1236 | 1352 |
| LMArena Russian | 1278 | 1385 |
| LMArena Spanish | 1267 | 1419 |
| LMArena French | — | 1421 |

## Instruction Following

- gpt-oss-20b: 61.8 (#240)
- Step 3.5 Flash: 73.1 (#124)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1236 | 1385 |
| IFEval | 73.2% | — |

## Long Context

- gpt-oss-20b: 37.9 (#209)
- Step 3.5 Flash: 42.8 (#117)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1250 | 1402 |

## Writing & Preference

- gpt-oss-20b: 35.5 (#265)
- Step 3.5 Flash: 58.8 (#113)

| Benchmark | gpt-oss-20b | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1287 | 1403 |
| LMArena Creative Writing | 1201 | 1357 |
| LMArena Multi-Turn | 1268 | 1405 |
| EQ-Bench Creative Writing | 666 | — |
| WildBench | 73.7% | — |

## FAQ

### Is gpt-oss-20b better than Step 3.5 Flash?

Step 3.5 Flash is the stronger model overall, scoring 42.3 to 32.5 on the Noometry Index. gpt-oss-20b costs 4.2× less per token, which makes it the better buy when Step 3.5 Flash's lead doesn't matter for your workload.

### Which is cheaper, gpt-oss-20b or Step 3.5 Flash?

gpt-oss-20b is cheaper. It lists at $0.018 per million input tokens and $0.09 per million output tokens; Step 3.5 Flash lists at $0.10 and $0.30.

### Is gpt-oss-20b or Step 3.5 Flash better for coding?

Step 3.5 Flash scores higher on coding benchmarks: 42.4 versus 37.6 in the Noometry coding category.

### Which has the bigger context window?

Step 3.5 Flash does, with 256K tokens against 131K.

### How many benchmarks do gpt-oss-20b and Step 3.5 Flash share?

16 benchmarks have published results for both models. gpt-oss-20b has 34 scored results on Noometry and Step 3.5 Flash has 19.