# o1 vs Step 3.5 Flash

> Step 3.5 Flash is the stronger model overall, scoring 42.3 to 40.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/o1-vs-step-3-5-flash
- Last updated: 2026-10-12
- Shared benchmarks: 17

## Summary

- They share 17 benchmarks with published results for both. o1 scores higher in 5 categories and Step 3.5 Flash in 3 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in long context, where o1 leads 50.3 to 42.8.
- Step 3.5 Flash is cheaper at $0.10 / $0.30 per million input/output tokens, against $15 / $60 for o1.
- Step 3.5 Flash accepts more context: 256K tokens versus 200K.
- Step 3.5 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | o1 | Step 3.5 Flash |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 40.9 | 42.3 |
| Rank | 143 | 116 |
| Context | 200K | 256K |
| Input $/M | $15 | $0.10 |
| Output $/M | $60 | $0.30 |
| Weights | Proprietary | Open |

## Coding

- o1: 46.1 (#70)
- Step 3.5 Flash: 42.4 (#105)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1367 | 1436 |
| Aider Polyglot | 61.7% | — |
| WeirdML | 47.6% | — |
| LiveBench Coding | 69.7% | — |
| CadEval | 56% | — |
| HumanEval+ | 89% | — |
| MBPP+ | 80.2% | — |

## Agentic & Tool Use

- o1: 24.6 (#117)
- Step 3.5 Flash: —

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| Cybench | 10% | — |
| METR Time Horizons | 51.1% | — |

## Reasoning

- o1: 27.9 (#111)
- Step 3.5 Flash: 22.2 (#202)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1371 | 1411 |
| SimpleBench | 41.7% | — |
| NYT Connections (extended) | — | 28.4% |
| ARC-AGI-1 | 30.7% | — |
| Chess Puzzles | 15% | — |
| EnigmaEval | 5.7% | — |
| LiveBench Reasoning | 91.6% | — |
| DTBench | 74.7% | — |
| LiveBench Data Analysis | 65.5% | — |
| LMCA | 22.3% | — |
| Epoch Capabilities Index | 141.91 | — |
| LiveBench | 75.7% | — |

## Math

- o1: 36.1 (#175)
- Step 3.5 Flash: 42.6 (#84)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1388 | 1408 |
| FrontierMath (Tiers 1-3) | 14.7% | — |
| MathArena Final-Answer Competitions | — | 66.8% |
| OTIS Mock AIME 2024-2025 | 73.3% | — |
| LiveBench Math | 80.3% | — |
| MATH Level 5 | 94.7% | — |
| FrontierMath (Feb 2025 set) | 9.3% | — |

## Knowledge

- o1: 41.5 (#110)
- Step 3.5 Flash: 39.6 (#132)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1361 | 1421 |
| GPQA Diamond | 76.8% | — |
| Humanity's Last Exam | 8% | — |
| SimpleQA Verified | 41.1% | — |
| Confabulations | 11.7% | — |

## Multimodal

- o1: 34.2 (#93)
- Step 3.5 Flash: —

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 1168 | — |
| GeoBench | 80% | — |
| VPCT | 37% | — |
| SpatialViz-Bench | 41.4% | — |

## Multilingual

- o1: 48.6 (#142)
- Step 3.5 Flash: 50.5 (#119)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1358 | 1385 |
| LMArena Chinese | 1394 | 1447 |
| LMArena French | 1344 | 1421 |
| LMArena German | 1337 | 1405 |
| LMArena Japanese | 1346 | 1354 |
| LMArena Korean | 1396 | 1352 |
| LMArena Russian | 1356 | 1385 |
| LMArena Spanish | 1345 | 1419 |

## Instruction Following

- o1: 74.8 (#86)
- Step 3.5 Flash: 73.1 (#124)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1367 | 1385 |
| LiveBench Instruction Following | 81.5% | — |

## Long Context

- o1: 50.3 (#9)
- Step 3.5 Flash: 42.8 (#117)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1378 | 1402 |
| Fiction.LiveBench | 83.3% | — |

## Writing & Preference

- o1: 55.6 (#144)
- Step 3.5 Flash: 58.8 (#113)

| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1366 | 1403 |
| LMArena Creative Writing | 1348 | 1357 |
| LMArena Multi-Turn | 1369 | 1405 |
| Short-Story Creative Writing | 70.2% | — |
| LiveBench Language | 65.4% | — |

## FAQ

### Is o1 better than Step 3.5 Flash?

Step 3.5 Flash is the stronger model overall, scoring 42.3 to 40.9 on the Noometry Index.

### Which is cheaper, o1 or Step 3.5 Flash?

Step 3.5 Flash is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; o1 lists at $15 and $60.

### Is o1 or Step 3.5 Flash better for coding?

o1 scores higher on coding benchmarks: 46.1 versus 42.4 in the Noometry coding category.

### Which has the bigger context window?

Step 3.5 Flash does, with 256K tokens against 200K.

### How many benchmarks do o1 and Step 3.5 Flash share?

17 benchmarks have published results for both models. o1 has 52 scored results on Noometry and Step 3.5 Flash has 19.