Model comparison
o1 vs Step 3.5 Flash
Step 3.5 Flash is the stronger model overall, scoring 41.7 to 40.6 on the Noometry Index.
Last verified . 17 shared benchmarks.
StepFunSummary
- 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.
Side by side
| o1 | Step 3.5 Flash | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 40.6 | 41.7 |
| Released | 2024-09-12 | 2026-01-29 |
| Weights | Proprietary | Open |
| Context window | 200K | 256K |
| Max output | 100K | 256K |
| Input $ / M tokens | $15 | $0.10 |
| Output $ / M tokens | $60 | $0.30 |
| Results tracked | 52 | 19 |
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Category by category
Coding o1 leads
o1: 45.7 (#64), Step 3.5 Flash: 41.7 (#106)
| 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 Not comparable
o1: 24.3 (#111), Step 3.5 Flash: —
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| Cybench | 10% | — |
| METR Time Horizons | 51.1% | — |
Reasoning o1 leads
o1: 27.5 (#103), Step 3.5 Flash: 21.2 (#202)
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1372 | 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 | 141.92 | — |
| LiveBench | 75.7% | — |
Math Step 3.5 Flash leads
o1: 34.9 (#150), Step 3.5 Flash: 40.6 (#77)
| 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 leads
o1: 41.5 (#101), Step 3.5 Flash: 39.0 (#127)
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1362 | 1422 |
| GPQA Diamond | 76.8% | — |
| Humanity's Last Exam | 8% | — |
| SimpleQA Verified | 41.1% | — |
| Confabulations | 11.7% | — |
Multimodal Not comparable
o1: 33.6 (#87), Step 3.5 Flash: —
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 1168 | — |
| GeoBench | 80% | — |
| VPCT | 37% | — |
| SpatialViz-Bench | 41.4% | — |
Multilingual Step 3.5 Flash leads
o1: 48.8 (#137), Step 3.5 Flash: 50.7 (#115)
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1359 | 1386 |
| LMArena Chinese | 1394 | 1448 |
| LMArena French | 1343 | 1421 |
| LMArena German | 1337 | 1404 |
| LMArena Japanese | 1346 | 1353 |
| LMArena Korean | 1396 | 1350 |
| LMArena Russian | 1356 | 1385 |
| LMArena Spanish | 1345 | 1419 |
Instruction Following o1 leads
o1: 75.0 (#82), Step 3.5 Flash: 73.3 (#119)
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1368 | 1385 |
| LiveBench Instruction Following | 81.5% | — |
Long Context o1 leads
o1: 50.3 (#9), Step 3.5 Flash: 42.8 (#112)
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1378 | 1402 |
| Fiction.LiveBench | 83.3% | — |
Writing & Preference Step 3.5 Flash leads
o1: 55.8 (#139), Step 3.5 Flash: 59.0 (#108)
| Benchmark | o1 | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1366 | 1403 |
| LMArena Creative Writing | 1347 | 1357 |
| LMArena Multi-Turn | 1368 | 1405 |
| Short-Story Creative Writing | 70.2% | — |
| LiveBench Language | 65.4% | — |
Frequently asked questions
Is o1 better than Step 3.5 Flash?
Step 3.5 Flash is the stronger model overall, scoring 41.7 to 40.6 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: 45.7 versus 41.7 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.