Step 5 Preview: Pricing & Open Weights

Step 5 Preview pricing starts at $1.00 input and $2.70 output per 1M tokens on OpenRouter, with 1M context. See specs and open-weights status for today.

StepFun launched Step 5 Preview on October 8, 2026 as its flagship model for agentic work: software engineering, professional knowledge tasks and finance. It is a sparse Mixture-of-Experts model with 600B total parameters and 27B active per token, a 1M-token context window and vision input. This page covers verified API pricing, how to try it today and the careful open-weights status as of the morning of October 15, 2026 (Asia/Saigon).

What is Step 5 Preview?

Step 5 Preview is StepFun’s newest frontier model for long-running agent work. StepFun’s product page says it handles large codebases and documents, calls tools in parallel, supports configurable reasoning effort and accepts text, image and video input. On OpenRouter the model id is stepfun/step-5-preview, with up to 64K completion tokens.

Don’t confuse the hosted API with open weights. The API is available now through StepFun’s products and third-party gateways such as OpenRouter. Open weights are a separate release StepFun scheduled for October 15.

Step 5 Preview Pricing (2026)

We checked the OpenRouter Step 5 Preview listing on October 15, 2026. List rates match what StepFun and OpenRouter announced at launch:

Source	Input / 1M	Output / 1M	Cache read / 1M	Context
OpenRouter (stepfun/step-5-preview)	$1.00	$2.70	$0.05	1,000,000 tokens

What that means in money: a request with 100,000 input tokens and 10,000 output tokens costs about $0.127 ($0.10 in + $0.027 out). If those 100,000 input tokens are cache hits at $0.05 per 1M, the input part drops to $0.005. OpenRouter’s weighted average input on October 15 sat near $0.13 per 1M with a high cache-hit rate, which shows how much caching can cut the bill for agents that resend the same context.

For comparison, see our Claude Sonnet 4.5 page and the GPT-6 Astra vs Sol breakdown. Step 5 Preview’s $1/$2.70 list sits well below Opus-tier $4/$20 pricing and far below Astra’s $10/$50.

Open weights status (morning of October 15)

StepFun’s official Step 5 Preview page still said on the morning of October 15, 2026: “The model will be released with open weights on October 15.” That is a scheduled date, not proof that weights already shipped.

We also checked the official Hugging Face org stepfun-ai that morning. There was no Step-5 repository under stepfun-ai. Third-party mirrors such as SHSLab/Step-5-Preview-BF16 and various GGUF/FP8 forks exist on Hugging Face, but those are not the official StepFun upload. Do not treat a community mirror as StepFun’s official BF16 release.

• What is true today: API access via StepFun products and OpenRouter (stepfun/step-5-preview).
• What StepFun scheduled: BF16 open weights on October 15.
• What we could not confirm this morning: an official stepfun-ai Hugging Face Step-5 repo or a product-page flip to “weights available now.”
• What to ignore: claims that official open weights already shipped, unless stepfun.com or stepfun-ai HF explicitly shows them.

Specs and capabilities

Spec	Detail
Architecture	Sparse MoE, 600B total / 27B active per token
Context	1,000,000 tokens
Max output (OpenRouter)	64,000 tokens
Inputs	Text, image, video
Output	Text
Tool calling	Supported (parallel tools, structured JSON)
Reasoning effort	Configurable (low / medium / high / xhigh on StepFun side)
Released (hosted)	October 8, 2026

StepFun publishes its own benchmark table on the product page (DeepSWE, StepCodeBench, FrontierFinance and others). Treat those as vendor numbers. For a broader model pick, see our best AI model guide and the Qwen 4 release date tracker for the open-weight race.

How to try Step 5 Preview

1. OpenRouter: set the model to stepfun/step-5-preview with an OpenRouter API key.
2. StepFun products / API: use StepFun’s own apps and developer docs linked from the product page.
3. Coding agents: some third-party coding tools listed Step 5 Preview at launch (check each tool’s current model picker).
4. Local weights: wait for an official stepfun-ai Hugging Face upload before trusting a “Step-5” checkpoint for production.

Limitations

• Open weights not confirmed official yet: as of morning Oct 15 ICT, stepfun-ai HF had no Step-5 repo.
• Single OpenRouter provider: requests go to StepFun only; no multi-provider failover listed.
• Vendor benchmarks: StepFun’s table is not an independent leaderboard.
• Community mirrors: third-party HF copies may differ from any future official release.

Step 5 Preview alternatives

• Claude Sonnet 4.5: Anthropic mid-tier for coding and agents.
• GPT-6 Astra vs Sol: OpenAI flagship pair with clear list prices.
• Best AI model guide: how we compare frontier models without chasing every launch score.
• Qwen 4 release date: another open-weight timeline to watch.

Step 5 Preview is one of the stronger price/performance frontier options live today at $1/$2.70 per 1M tokens with a 1M context. For hosted use, OpenRouter is the easiest verified path.

Treat open weights carefully: StepFun scheduled them for October 15, but as of this morning the official site still listed that date and stepfun-ai had no Step-5 Hugging Face repo. Use the API now; wait for an official upload before trusting local checkpoints.