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Hy4 preview vs Step-3.5-Flash

Hy4 preview leads the LLM Stats Score 51.5 to 37.3.

Tencent · StepFun · Updated for 2026

Which is better?

Hy4 preview leads the overall LLM Stats Score 51.5 to 37.3, ranking #10 overall.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Hy4 preview

  • overall performance matters — it scores 51.5 and ranks #10 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you want the most recent training data — it shipped Aug 2026

Choose Step-3.5-Flash

  • you want predictable pricing at $0.10/M input and $0.40/M output

At a glance

The differences that matter most.

Hy4 preview
Tencent
Step-3.5-Flash
StepFun
Core performance indexes
LLM Stats Score
51.5
#10
37.3
#61
Reasoning
51.2
#8
37.3
#62
Coding
40.9
#10
20.4
#88
Agents
37.1
#11
15.3
#74
Cost, coverage & limits
Benchmark wins
—
—
Input price
— / M
$0.10 / M
Output price
— / M
$0.40 / M
Context window
—
65,536

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Hy4 preview
Step-3.5-Flash
Math
40.3#12
33.8#50
Tool use
32.6#7
12.9#93
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

32 reported for Hy4 preview · 7 for Step-3.5-Flash

No common benchmarks found

Hy4 preview and Step-3.5-Flashdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Model Size

Parameter count comparison

574.0B diff

Hy4 preview has 574.0B more parameters than Step-3.5-Flash, making it 292.9% larger.

Tencent
Hy4 preview
770.0Bparameters
StepFun
Step-3.5-Flash
196.0Bparameters
770.0B
Hy4 preview
196.0B
Step-3.5-Flash

Context Window

Maximum input and output token capacity

Only Step-3.5-Flash specifies input context (65,536 tokens). Only Step-3.5-Flash specifies output context (8,192 tokens).

Tencent
Hy4 preview
Input- tokens
Output- tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Tue Sep 01 2026 • llm-stats.com

License

Usage and distribution terms

Both models are licensed under Apache 2.0.

Both models share the same licensing terms, providing consistent usage rights.

Hy4 preview

Apache 2.0

Open weights

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Hy4 preview was released on 2026-08-28, while Step-3.5-Flash was released on 2026-02-02.

Hy4 preview is 7 months newer than Step-3.5-Flash.

Hy4 preview

Aug 28, 2026

3 days ago

6mo newer
Step-3.5-Flash

Feb 2, 2026

7 months ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Hy4 preview and Step-3.5-Flash side-by-side, then vote on the output you prefer.

Hy4 preview
✓ Preferred
Step-3.5-Flash
Open in Playground

FAQ

Common questions about Hy4 preview vs Step-3.5-Flash.

Which is better, Hy4 preview or Step-3.5-Flash?

Hy4 preview leads the LLM Stats Score 51.5 to 37.3. Hy4 preview is made by Tencent and Step-3.5-Flash is made by StepFun. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Hy4 preview compare to Step-3.5-Flash in benchmarks?

Hy4 preview scores GPQA: 92.3%, Terminal-Bench 2.1: 85.4%, WideSearch: 83.9%, MCP Atlas: 83.7%, SWE-bench Multilingual: 82.9%. Step-3.5-Flash scores AIME 2025: 97.3%, Tau-bench: 88.2%, LiveCodeBench v6: 86.4%, IMO-AnswerBench: 85.4%, SWE-Bench Verified: 74.4%.

What are the context window sizes for Hy4 preview and Step-3.5-Flash?

Hy4 preview supports an unknown number of tokens and Step-3.5-Flash supports 66K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Hy4 preview and Step-3.5-Flash?

Key differences include LLM Stats Score (51.5 vs 37.3). See the full comparison above for benchmark-by-benchmark results.

Who makes Hy4 preview and Step-3.5-Flash?

Hy4 preview is developed by Tencent and Step-3.5-Flash is developed by StepFun.

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