Model comparison
gpt-oss-120b vs Step 5 Preview
Step 5 Preview is the stronger model overall, scoring 47.9 to 36.3 on the Noometry Index. gpt-oss-120b costs 20× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.
Last verified . 15 shared benchmarks.
StepFunSummary
- They share 15 benchmarks with published results for both. gpt-oss-120b scores higher in 2 categories and Step 5 Preview in 6 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Step 5 Preview leads 40.0 to 20.0.
- The biggest single-benchmark swing is SciCode: 36% for gpt-oss-120b and 58.9% for Step 5 Preview.
- gpt-oss-120b is cheaper at $0.037 / $0.17 per million input/output tokens, against $1 / $2.70 for Step 5 Preview.
- Step 5 Preview accepts more context: 1.02M tokens versus 131K.
- gpt-oss-120b has downloadable open weights; the other is API-only.
Side by side
| gpt-oss-120b | Step 5 Preview | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 36.3 | 47.9 |
| Released | 2025-08-05 | 2026-09-16 |
| Weights | Open | Proprietary |
| Context window | 131K | 1.02M |
| Max output | 41K | 66K |
| Input $ / M tokens | $0.037 | $1 |
| Output $ / M tokens | $0.17 | $2.70 |
| Results tracked | 48 | 18 |
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Category by category
Coding Step 5 Preview leads
gpt-oss-120b: 33.5 (#256), Step 5 Preview: 51.8 (#36)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| SciCode | 36% | 58.9% |
| LMArena Coding | 1380 | 1480 |
| SWE-bench Verified (bash only) | 26% | — |
| Aider Polyglot | 41.8% | — |
| LMArena WebDev | — | 1564 |
| WeirdML | 48.2% | — |
| ALE-Bench | 575.62 | — |
| AlgoTune | 1.41 | — |
Agentic & Tool Use Not comparable
gpt-oss-120b: 12.2 (#153), Step 5 Preview: —
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| Terminal-Bench | 18.7% | — |
| APEX-Agents | 4.4% | — |
| METR Time Horizons | 56.6% | — |
| Vending-Bench 2 | -21.53 | — |
Reasoning Step 5 Preview leads
gpt-oss-120b: 20.0 (#245), Step 5 Preview: 40.0 (#57)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| CritPt | 1.1% | 20.9% |
| LMArena Hard Prompts | 1364 | 1465 |
| SimpleBench | 22.1% | — |
| Kagi LLM Benchmark | 58.6% | — |
| Chess Puzzles | 20% | — |
| Mystery Game Puzzles | 2% | — |
| DTBench | 76.3% | — |
| LMCA | 22.1% | — |
| Surface Evolver Bench | 25% | — |
| Epoch Capabilities Index | 139.93 | — |
Math gpt-oss-120b leads
gpt-oss-120b: 52.5 (#50), Step 5 Preview: 46.1 (#72)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Math | 1389 | 1470 |
| OTIS Mock AIME 2024-2025 | 88.9% | — |
| ProofBench | — | 42% |
| Omni-MATH | 68.8% | — |
Knowledge gpt-oss-120b leads
gpt-oss-120b: 42.4 (#96), Step 5 Preview: 41.2 (#112)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Expert | 1356 | 1470 |
| GPQA Diamond | 75.8% | — |
| MMLU-Pro | 79.5% | — |
| Confabulations | 15.7% | — |
| Vectara Hallucination Rate | 14.2% | — |
| GPQA (HELM) | 68.4% | — |
Multimodal Not comparable
gpt-oss-120b: —, Step 5 Preview: 41.0 (#41)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Vision | — | 1267 |
Multilingual Step 5 Preview leads
gpt-oss-120b: 48.0 (#147), Step 5 Preview: 53.8 (#54)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Non-English | 1351 | 1432 |
| LMArena Chinese | 1385 | 1519 |
| LMArena Russian | 1343 | 1436 |
| LMArena Spanish | 1389 | 1439 |
| LMArena French | 1369 | — |
| LMArena German | 1353 | — |
| LMArena Japanese | 1331 | — |
| LMArena Korean | 1282 | — |
Instruction Following Step 5 Preview leads
gpt-oss-120b: 69.3 (#173), Step 5 Preview: 76.0 (#50)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Instruction Following | 1318 | 1444 |
| IFEval | 83.6% | — |
Long Context Step 5 Preview leads
gpt-oss-120b: 31.4 (#278), Step 5 Preview: 44.5 (#64)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Longer Query | 1319 | 1455 |
| Fiction.LiveBench | 44.4% | — |
Writing & Preference Step 5 Preview leads
gpt-oss-120b: 46.5 (#217), Step 5 Preview: 62.8 (#71)
| Benchmark | gpt-oss-120b | Step 5 Preview |
|---|---|---|
| LMArena Text | 1365 | 1442 |
| LMArena Creative Writing | 1275 | 1410 |
| LMArena Multi-Turn | 1340 | 1447 |
| Short-Story Creative Writing | 77.1% | — |
| EQ-Bench Creative Writing | 961 | — |
| WildBench | 84.5% | — |
Frequently asked questions
Is gpt-oss-120b better than Step 5 Preview?
Step 5 Preview is the stronger model overall, scoring 47.9 to 36.3 on the Noometry Index. gpt-oss-120b costs 20× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.
Which is cheaper, gpt-oss-120b or Step 5 Preview?
gpt-oss-120b is cheaper. It lists at $0.037 per million input tokens and $0.17 per million output tokens; Step 5 Preview lists at $1 and $2.70.
Is gpt-oss-120b or Step 5 Preview better for coding?
Step 5 Preview scores higher on coding benchmarks: 51.8 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
Step 5 Preview does, with 1.02M tokens against 131K.
How many benchmarks do gpt-oss-120b and Step 5 Preview share?
15 benchmarks have published results for both models. gpt-oss-120b has 48 scored results on Noometry and Step 5 Preview has 18.