---
title: "StepFun: Step 3.5 Flash — price, capability and what beats it · Undominated.ai"
canonical: https://undominated.ai/models/stepfun__step-3.5-flash/
description: "StepFun: Step 3.5 Flash: $0.100/M in, $0.300/M out. Independent capability scores, context-tier pricing, and the models that are both better and cheaper."
---

# StepFun: Step 3.5 Flash — price, capability and what beats it · Undominated.ai

> StepFun: Step 3.5 Flash: $0.100/M in, $0.300/M out. Independent capability scores, context-tier pricing, and the models that are both better and cheaper.

[Leaderboard](/) / StepFun

# Step 3.5 Flash

StepFun · released 2026-01-29

 $0.150 per million tokens, balanced Balanced Summarise Chat Code gen Agentic

## No independent quality score.

No benchmark we track has measured this model. That is not the same as measuring it and finding it wanting — we simply cannot rank it, so we do not.

### Every price dimension

| Input | $0.100 /M |
| --- | --- |
| Output | $0.300 /M |

### Independent scores

| LMArena Elo | 1403.8 default |
| --- | --- |

Sources are listed separately rather than averaged. Across the 62 models both have scored they correlate at r = 0.806 — close agreement overall, but four models rank very differently between them, and a blended score would hide exactly those.

### Capability

| Context window | 262K |
| --- | --- |
| Max output | 66K |
| Input modes | text |
| Tool use | yes |
| Reasoning | always on |

### Provenance

| Price source | openrouter.ai |
| --- | --- |
| Fetched | 2026-08-24 |
| Quality data | unrated |

Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....