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AI Choice Engine

StepFun

Step 5 Preview

Step 5 Preview is a StepFun model with 1M context, $1 in / $2.70 out per million tokens, last verified September 26, 2026. Open weights: no. Public-board scores are linked to the publisher; vendor-only figures stay in the watch-out, not on the board.

Step 5 Preview is StepFun's new frontier reasoning model — a 1M-context, vision-input API preview that lands near Kimi K3 and GLM 5.3 on the Artificial Analysis index at a lower price.

Catalog record checked September 26, 2026Individual provider fields may change

AI model specification details
SpecificationStep 5 Preview
ProviderStepFun
TierFrontier
Context window1M
Max outputNot verifiedUnverified
Input / 1M tokens$1
Output / 1M tokens$2.70
WeightsClosed
Parameters600B total / 27B active MoE (StepFun)
Reasoning levelsNot verifiedUnverified
Modalitiestext, image
API model idstep-5-preview
ReleasedSeptember 18, 2026

Pricing tiers: $1.00/$2.70 per MTok on the StepFun platform (cache-hit input $0.05); StepFun lists it under Multimodal Reasoning Models and says output tokens include reasoning. No max-output figure is published. StepFun says open weights follow on 2026-10-15. Release date per Artificial Analysis's listing (StepFun's launch page is undated).

Verified evidence

Published benchmark results

Each result keeps its source and measurement date visible. A missing benchmark is not treated as a zero.

Published benchmark results for Step 5 Preview
BenchmarkScoreMeasuredSource
Artificial Analysis Intelligence Index43.72026-09-26Artificial Analysis · View source

Best for

  • Long-context work on a budget
  • Chinese + English
  • Early testing before the open-weight drop

Watch out

Preview: weights are promised for 2026-10-15 but not yet released, and its max output is unpublished and the launch benchmarks are vendor-run.

History

Step 5 Preview timeline

Release and status events for this model that passed two-source verification — dated, sourced, and linked.

  • Step 5 PreviewLimited previewSeptember 18, 2026

    StepFun opens API access to Step 5 Preview ($1.00/$2.70 per MTok, 1M context) and promises open weights on 2026-10-15.

    StepFun platform pricing (step-5-preview)

Source receipts

Catalog figures for this model were checked against the following sources.

Common questions

Step 5 Preview

Answered from the verified figures on this page rather than general guidance.

How much does Step 5 Preview cost per million tokens?
Step 5 Preview is listed at $1 per million input tokens and $2.70 per million output tokens at standard rates. Output tokens usually dominate real bills, so weigh the output rate more heavily than the input rate. $1.00/$2.70 per MTok on the StepFun platform (cache-hit input $0.05); StepFun lists it under Multimodal Reasoning Models and says output tokens include reasoning. No max-output figure is published. StepFun says open weights follow on 2026-10-15. Release date per Artificial Analysis's listing (StepFun's launch page is undated).
What is Step 5 Preview's context window?
Step 5 Preview accepts about 1M tokens of context. That only matters if you routinely send very long documents, large codebases, or multi-turn histories that approach that limit.
What is Step 5 Preview best for?
Step 5 Preview is a frontier tier from StepFun. It suits long-context work on a budget, chinese + english, early testing before the open-weight drop. Preview: weights are promised for 2026-10-15 but not yet released, and its max output is unpublished and the launch benchmarks are vendor-run.
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