Model Comparison

Gemini 3.1 Pro vs Step-3.5-Flash

Gemini 3.1 Pro significantly outperforms across most benchmarks. Step-3.5-Flash is 32.1x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

3 benchmarks

Gemini 3.1 Pro outperforms in 3 benchmarks (BrowseComp, SWE-Bench Verified, Terminal-Bench 2.0), while Step-3.5-Flash is better at 0 benchmarks.

Gemini 3.1 Pro significantly outperforms across most benchmarks.

Tue Apr 07 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Step-3.5-Flash costs less

For input processing, Gemini 3.1 Pro ($2.50/1M tokens) is 25.0x more expensive than Step-3.5-Flash ($0.10/1M tokens).

For output processing, Gemini 3.1 Pro ($15.00/1M tokens) is 37.5x more expensive than Step-3.5-Flash ($0.40/1M tokens).

In conclusion, Gemini 3.1 Pro is more expensive than Step-3.5-Flash.*

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

Lowest available price from all providers
Tue Apr 07 2026 • llm-stats.com
Google
Gemini 3.1 Pro
Input tokens$2.50
Output tokens$15.00
Best providerGoogle
StepFun
Step-3.5-Flash
Input tokens$0.10
Output tokens$0.40
Best providerStepFun
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Gemini 3.1 Pro accepts 1,048,576 input tokens compared to Step-3.5-Flash's 65,536 tokens. Gemini 3.1 Pro can generate longer responses up to 65,536 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

Google
Gemini 3.1 Pro
Input1,048,576 tokens
Output65,536 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Tue Apr 07 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Gemini 3.1 Pro supports multimodal inputs, whereas Step-3.5-Flash does not.

Gemini 3.1 Pro can handle both text and other forms of data like images, making it suitable for multimodal applications.

Gemini 3.1 Pro

Text
Images
Audio
Video

Step-3.5-Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Gemini 3.1 Pro 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.

Gemini 3.1 Pro

Proprietary

Closed source

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Gemini 3.1 Pro was released on 2026-02-19, while Step-3.5-Flash was released on 2026-02-02.

Gemini 3.1 Pro is 1 month newer than Step-3.5-Flash.

Gemini 3.1 Pro

Feb 19, 2026

1 months ago

2w newer
Step-3.5-Flash

Feb 2, 2026

2 months ago

Knowledge Cutoff

When training data ends

Gemini 3.1 Pro has a documented knowledge cutoff of 2025-01-31, while Step-3.5-Flash's cutoff date is not specified.

We can confirm Gemini 3.1 Pro's training data extends to 2025-01-31, but cannot make a direct comparison without Step-3.5-Flash's cutoff date.

Gemini 3.1 Pro

Jan 2025

Step-3.5-Flash

—

Provider Availability

Gemini 3.1 Pro is available from Google. Step-3.5-Flash is available from StepFun.

Gemini 3.1 Pro

google logo
Google
Input Price:Input: $2.50/1MOutput Price:Output: $15.00/1M

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

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Key Takeaways

Google
Larger context window (1,048,576 tokens)
Supports multimodal inputs
Higher BrowseComp score (85.9% vs 69.0%)
Higher SWE-Bench Verified score (80.6% vs 74.4%)
Higher Terminal-Bench 2.0 score (68.5% vs 51.0%)
StepFun
Less expensive input tokens
Less expensive output tokens
Has open weights

Detailed Comparison

AI Model Comparison Table
Feature
Google
Gemini 3.1 Pro
StepFun
Step-3.5-Flash

FAQ

Common questions about Gemini 3.1 Pro vs Step-3.5-Flash

Gemini 3.1 Pro significantly outperforms across most benchmarks. Gemini 3.1 Pro is made by Google and Step-3.5-Flash is made by StepFun. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.
Gemini 3.1 Pro scores t2-bench: 99.3%, LiveCodeBench Pro: 96.2%, GPQA: 94.3%, MMMLU: 92.6%, BrowseComp: 85.9%. 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%.
Step-3.5-Flash is 25.0x cheaper for input tokens. Gemini 3.1 Pro costs $2.50/M input and $15.00/M output via google. Step-3.5-Flash costs $0.10/M input and $0.40/M output via stepfun.
Gemini 3.1 Pro 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.
Key differences include context window (1.0M vs 66K), input pricing ($2.50 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.
Gemini 3.1 Pro is developed by Google and Step-3.5-Flash is developed by StepFun.