Step 5 Preview
StepFun
Key facts · verified Oct 14, 2026
Step 5 Preview is a StepFun model released on 20 Sept 2026. Its API price is $1 per million input tokens and $2.70 per million output tokens. Its context window is 1M tokens. It ranks #86 on LMArena's text leaderboard (Elo 1446, read 14 Oct 2026). Source: stepfun.com.
Step 5 Preview is StepFun's agent model, listed on StepFun's site on September 20, 2026. It is a mixture-of-experts model with 600 billion total and 27 billion active parameters and a 1M-token context window. StepFun lists API pricing of $1 per million input tokens and $2.70 per million output tokens, and has announced open weights for October 15, 2026.
Pricing & specs checkedSource: vendor documentation · checked Oct 14, 2026LMArena: 1446 Elo (rank 86) · source · retrieved Oct 14, 2026
Key Features
Long Context Agents
Full Specifications
$1 / $2.70 per million tokens | |
|---|---|
| Identity | |
| Developer | StepFun |
| Released | Sep 2026 |
| Licence | Not yet stated (open weights announced for 15 Oct 2026) |
| Cost | |
| Blended $/1M tokensinput × 0.75 + output × 0.25 | $1.425 / 1M tokens |
| Input price | $1.000 / 1M tokens |
| Output price | $2.700 / 1M tokens |
| Capacity | |
| Context window | 1M tokens |
| Access | |
| API | Yes |
| Measured quality | |
| LMArena Elo | 1446 (checked Oct 2026) |
| LMArena rank | Rank 86 |
| Elo per dollarLMArena Elo ÷ blended $/1M tokens | 1015 |