# StepFun launches Step 5 Preview with 1M-token context and $1 input pricing

Digest AI · Generative AI & Models · published 2026-09-21T06:37:18Z

Canonical: https://digestai.news/story/stepfun-launches-step-5-preview-with-1m-token-context-and-1-input-pric

## Summary

StepFun announced Step 5 Preview, its flagship mixture‑of‑experts model aimed at agentic software engineering, knowledge work, and finance tasks. The model totals about 600 billion parameters but activates roughly 27 billion per token, giving a 1 million‑token context window and supporting text, image, and video input. StepFun says the model is available now via a hosted API and on its platform, with open‑weight release slated for October 15 2026.

The company lists API pricing at $1.00 per 1 M input tokens and $2.70 per 1 M output tokens. Internal benchmarks show a 3× end‑to‑end speedup for long‑horizon reinforcement‑learning workloads and a throughput of 99.8 tokens per second. On StepFun’s own coding benchmarks the model scored 67.7 on DeepSWE v1.1, 49.0 on StepCodeBench, and 80.5 on ProgramBench, while independent analysis from Artificial Analysis gave it an Intelligence Index score of 44, well above the 24 median for similarly priced models. The model also demonstrated hardware tuning gains, reaching 508 TFLOPS on an H100 kernel compared with 493 TFLOPS for Claude Opus 5.

## Key points

- Step 5 Preview is a 600B‑parameter MoE model activating 27B weights per token, with a 1 M‑token context window.
- API pricing is $1.00 per 1 M input tokens and $2.70 per 1 M output tokens.
- Open weights are planned for release on October 15 2026; until then the model is available via hosted API only.

## Why it matters

A 1 M‑token context MoE model at $1 per million input tokens lowers cost for long‑horizon agentic tasks, enabling cheaper, scalable AI agents for coding, knowledge work, and finance.

## Sources

1. [StepFun Launches Step 5 Preview: A 600B-Total, 27B-Active MoE Model With 1M Context for Long-Horizon Agentic Work](https://marktechpost.com/2026/09/20/stepfun-launches-step-5-preview) (MarkTechPost, 2026-09-21)

Part of the developing story: [StepFun Unveils Massive AI Context Upgrade](https://digestai.news/thread/this-looks-promising-stepfun-ai-step-5-preview-bf16-hugging-face) (2 stories)

## Cite

Digest AI, "StepFun launches Step 5 Preview with 1M-token context and $1 input pricing", 21 September 2026, https://digestai.news/story/stepfun-launches-step-5-preview-with-1m-token-context-and-1-input-pric

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