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Particle-1 vs Step-3.5-Flash

Particle-1 and Step-3.5-Flash are closely matched at 31.9 and 36.5 on the LLM Stats Score. Step-3.5-Flash is 2.5x cheaper per token.

Particle AI · StepFun · Updated for 2026

Which is better?

Particle-1 and Step-3.5-Flash are closely matched on the overall LLM Stats Score at 31.9 and 36.5.

On price, Step-3.5-Flash is roughly 2.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Particle-1 also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.

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

Choose Particle-1

  • you process long inputs — it offers a 1,048,576 token context window
  • you want the most recent training data — it shipped Oct 2026

Choose Step-3.5-Flash

  • cost matters — it's about 2.5x cheaper per token
  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

Particle-1
Particle AI
Step-3.5-Flash
StepFun
Core performance indexes
LLM Stats Score
31.9
#133
36.5
#94
Reasoning
31.2
#135
36.5
#94
Cost, coverage & limits
Benchmark wins
—
—
Input price
$0.25 / M
$0.10 / M
Output price
$1.00 / M
$0.40 / M
Context window
1,048,576
65,536

Individual benchmarks

3 reported for Particle-1 · 7 for Step-3.5-Flash

No common benchmarks found

Particle-1 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

Pricing Analysis

Price comparison per million tokens

Step-3.5-Flash costs less

For input processing, Particle-1 ($0.25/1M tokens) is 2.5x more expensive than Step-3.5-Flash ($0.10/1M tokens).

For output processing, Particle-1 ($1.00/1M tokens) is 2.5x more expensive than Step-3.5-Flash ($0.40/1M tokens).

In conclusion, Particle-1 is more expensive than Step-3.5-Flash.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Fri Oct 30 2026 • llm-stats.com
Particle AI
Particle-1
Input tokens$0.25
Output tokens$1.00
Best providerUnknown Organization
StepFun
Step-3.5-Flash
Input tokens$0.10
Output tokens$0.40
Best providerStepFun
Notice missing or incorrect data?

Context Window

Maximum input and output token capacity

Particle-1 accepts 1,048,576 input tokens compared to Step-3.5-Flash's 65,536 tokens. Particle-1 can generate longer responses up to 131,072 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

Particle AI
Particle-1
Input1,048,576 tokens
Output131,072 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Fri Oct 30 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Particle-1 supports multimodal inputs, whereas Step-3.5-Flash does not.

Particle-1 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Particle-1

Text
Images
Audio
Video

Step-3.5-Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Particle-1 is licensed under a proprietary license, while Step-3.5-Flash uses Apache 2.0.

License differences may affect how you can use these models in commercial or open-source projects.

Particle-1

Proprietary

Closed source

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Particle-1 was released on 2026-10-28, while Step-3.5-Flash was released on 2026-02-02.

Particle-1 is 9 months newer than Step-3.5-Flash.

Particle-1

Oct 28, 2026

2 days ago

8mo newer
Step-3.5-Flash

Feb 2, 2026

9 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

Provider Availability

Particle-1 is available from Particle AI. Step-3.5-Flash is available from StepFun.

Particle-1

particle-ai logo
Unknown Organization
Input Price:Input: $0.25/1MOutput Price:Output: $1.00/1M

Step-3.5-Flash

stepfun logo
StepFun
Input Price:Input: $0.10/1MOutput Price:Output: $0.40/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Particle-1 and Step-3.5-Flash side-by-side, then vote on the output you prefer.

Particle-1
✓ Preferred
Step-3.5-Flash
Open in Playground

FAQ

Common questions about Particle-1 vs Step-3.5-Flash.

Which is better, Particle-1 or Step-3.5-Flash?

Particle-1 and Step-3.5-Flash are closely matched on the LLM Stats Score at 31.9 and 36.5. Particle-1 is made by Particle AI 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 Particle-1 compare to Step-3.5-Flash in benchmarks?

Particle-1 scores GPQA: 90.4%, BabyVision: 89.2%, MMLU: 86.1%. 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%.

Is Particle-1 cheaper than Step-3.5-Flash?

Step-3.5-Flash is 2.5x cheaper for input tokens. Particle-1 costs $0.25/M input and $1.00/M output via particle-ai. Step-3.5-Flash costs $0.10/M input and $0.40/M output via stepfun.

What are the context window sizes for Particle-1 and Step-3.5-Flash?

Particle-1 supports 1.0M 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 Particle-1 and Step-3.5-Flash?

Key differences include LLM Stats Score (31.9 vs 36.5), context window (1.0M vs 66K), input pricing ($0.25 vs $0.10/M), multimodal support (yes vs no), licensing (Proprietary vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.

Who makes Particle-1 and Step-3.5-Flash?

Particle-1 is developed by Particle AI and Step-3.5-Flash is developed by StepFun.

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