Model Comparison

Gemini 3.1 Pro vs Gemini 3.5 Flash

Gemini 3.5 Flash shows notably better performance in the majority of benchmarks. Gemini 3.5 Flash is 1.7x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

8 benchmarks

Gemini 3.1 Pro outperforms in 2 benchmarks (ARC-AGI v2, Humanity's Last Exam), while Gemini 3.5 Flash is better at 6 benchmarks (GDPval-AA, MCP Atlas, MMMU-Pro, MRCR v2 (8-needle), SWE-Bench Pro, Terminal-Bench 2.0).

Gemini 3.5 Flash shows notably better performance in the majority of benchmarks.

Wed May 20 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Gemini 3.5 Flash costs less

For input processing, Gemini 3.1 Pro ($2.50/1M tokens) is 1.7x more expensive than Gemini 3.5 Flash ($1.50/1M tokens).

For output processing, Gemini 3.1 Pro ($15.00/1M tokens) is 1.7x more expensive than Gemini 3.5 Flash ($9.00/1M tokens).

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

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

Lowest available price from all providers
Wed May 20 2026 • llm-stats.com
Google
Gemini 3.1 Pro
Input tokens$2.50
Output tokens$15.00
Best providerGoogle
Google
Gemini 3.5 Flash
Input tokens$1.50
Output tokens$9.00
Best providerGoogle
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Context Window

Maximum input and output token capacity

Both models have the same input context window of 1,048,576 tokens. Both models can generate responses up to 65,536 tokens.

Google
Gemini 3.1 Pro
Input1,048,576 tokens
Output65,536 tokens
Google
Gemini 3.5 Flash
Input1,048,576 tokens
Output65,536 tokens
Wed May 20 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Gemini 3.1 Pro and Gemini 3.5 Flash support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Gemini 3.1 Pro

Text
Images
Audio
Video

Gemini 3.5 Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Gemini 3.1 Pro

Proprietary

Closed source

Gemini 3.5 Flash

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 3.1 Pro was released on 2026-02-19, while Gemini 3.5 Flash was released on 2026-05-19.

Gemini 3.5 Flash is 3 months newer than Gemini 3.1 Pro.

Gemini 3.1 Pro

Feb 19, 2026

3 months ago

Gemini 3.5 Flash

May 19, 2026

1 days ago

2mo newer

Knowledge Cutoff

When training data ends

Gemini 3.1 Pro has a knowledge cutoff of 2025-01-31, while Gemini 3.5 Flash has a cutoff of 2026-01-31.

Gemini 3.5 Flash has more recent training data (up to 2026-01-31), making it potentially better informed about events through that date compared to Gemini 3.1 Pro (2025-01-31).

Gemini 3.1 Pro

Jan 2025

Gemini 3.5 Flash

Jan 2026

1 yr newer

Provider Availability

Gemini 3.1 Pro is available from Google. Gemini 3.5 Flash is available from Google.

Gemini 3.1 Pro

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

Gemini 3.5 Flash

google logo
Google
Input Price:Input: $1.50/1MOutput Price:Output: $9.00/1M
* Prices shown are per million tokens

Outputs Comparison

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Key Takeaways

Google
Higher ARC-AGI v2 score (77.1% vs 72.1%)
Higher Humanity's Last Exam score (51.4% vs 40.2%)
Google
Less expensive input tokens
Less expensive output tokens
Higher GDPval-AA score (55.2% vs 43.9%)
Higher MCP Atlas score (83.6% vs 69.2%)
Higher MMMU-Pro score (83.6% vs 80.5%)
Higher MRCR v2 (8-needle) score (26.6% vs 26.3%)
Higher SWE-Bench Pro score (55.1% vs 54.2%)
Higher Terminal-Bench 2.0 score (76.2% vs 68.5%)

Detailed Comparison

AI Model Comparison Table
Feature
Google
Gemini 3.1 Pro
Google
Gemini 3.5 Flash

FAQ

Common questions about Gemini 3.1 Pro vs Gemini 3.5 Flash.

Which is better, Gemini 3.1 Pro or Gemini 3.5 Flash?

Gemini 3.5 Flash shows notably better performance in the majority of benchmarks. Gemini 3.1 Pro is made by Google and Gemini 3.5 Flash is made by Google. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Gemini 3.1 Pro compare to Gemini 3.5 Flash in benchmarks?

Gemini 3.1 Pro scores t2-bench: 99.3%, LiveCodeBench Pro: 96.2%, GPQA: 94.3%, MMMLU: 92.6%, BrowseComp: 85.9%. Gemini 3.5 Flash scores CharXiv-R: 84.2%, MCP Atlas: 83.6%, MMMU-Pro: 83.6%, OSWorld-Verified: 78.4%, Terminal-Bench 2.0: 76.2%.

Is Gemini 3.1 Pro cheaper than Gemini 3.5 Flash?

Gemini 3.5 Flash is 1.7x cheaper for input tokens. Gemini 3.1 Pro costs $2.50/M input and $15.00/M output via google. Gemini 3.5 Flash costs $1.50/M input and $9.00/M output via google.

What are the context window sizes for Gemini 3.1 Pro and Gemini 3.5 Flash?

Gemini 3.1 Pro supports 1.0M tokens and Gemini 3.5 Flash supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Gemini 3.1 Pro and Gemini 3.5 Flash?

Key differences include input pricing ($2.50 vs $1.50/M). See the full comparison above for benchmark-by-benchmark results.