Model Comparison

Gemini 3.1 Pro vs Grok-4.1 Fast ReasoningWhich is better in 2026?

Comparing Gemini 3.1 Pro and Grok-4.1 Fast Reasoning across benchmarks, pricing, and capabilities.

Verdict: Gemini 3.1 Pro vs Grok-4.1 Fast Reasoning — which is better?

Gemini 3.1 Pro (by Google) and Grok-4.1 Fast Reasoning (by xAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

On price, Grok-4.1 Fast Reasoning is roughly 20.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Grok-4.1 Fast Reasoning also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Gemini 3.1 Pro if…

  • you want the most recent training data — it shipped Feb 2026

Choose Grok-4.1 Fast Reasoning if…

  • cost matters — it's about 20.5x cheaper per token
  • you process long inputs — it offers a 2,000,000 token context window
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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Gemini 3.1 Pro and Grok-4.1 Fast Reasoning don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok-4.1 Fast Reasoning costs less

For input processing, Gemini 3.1 Pro ($2.50/1M tokens) is 12.5x more expensive than Grok-4.1 Fast Reasoning ($0.20/1M tokens).

For output processing, Gemini 3.1 Pro ($15.00/1M tokens) is 30.0x more expensive than Grok-4.1 Fast Reasoning ($0.50/1M tokens).

In conclusion, Gemini 3.1 Pro is more expensive than Grok-4.1 Fast Reasoning.*

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

Lowest available price from all providers
Mon Jun 08 2026 • llm-stats.com
Google
Gemini 3.1 Pro
Input tokens$2.50
Output tokens$15.00
Best providerGoogle
xAI
Grok-4.1 Fast Reasoning
Input tokens$0.20
Output tokens$0.50
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Grok-4.1 Fast Reasoning accepts 2,000,000 input tokens compared to Gemini 3.1 Pro's 1,048,576 tokens. Gemini 3.1 Pro can generate longer responses up to 65,536 tokens, while Grok-4.1 Fast Reasoning is limited to 30,000 tokens.

Google
Gemini 3.1 Pro
Input1,048,576 tokens
Output65,536 tokens
xAI
Grok-4.1 Fast Reasoning
Input2,000,000 tokens
Output30,000 tokens
Mon Jun 08 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Gemini 3.1 Pro and Grok-4.1 Fast Reasoning 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

Grok-4.1 Fast Reasoning

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

Grok-4.1 Fast Reasoning

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 3.1 Pro was released on 2026-02-19, while Grok-4.1 Fast Reasoning was released on 2025-11-17.

Gemini 3.1 Pro is 3 months newer than Grok-4.1 Fast Reasoning.

Gemini 3.1 Pro

Feb 19, 2026

3 months ago

3mo newer
Grok-4.1 Fast Reasoning

Nov 17, 2025

6 months ago

Knowledge Cutoff

When training data ends

Gemini 3.1 Pro has a documented knowledge cutoff of 2025-01-31, while Grok-4.1 Fast Reasoning'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 Grok-4.1 Fast Reasoning's cutoff date.

Gemini 3.1 Pro

Jan 2025

Grok-4.1 Fast Reasoning

—

Provider Availability

Gemini 3.1 Pro is available from Google. Grok-4.1 Fast Reasoning is available from xAI.

Gemini 3.1 Pro

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

Grok-4.1 Fast Reasoning

xai logo
xAI
Input Price:Input: $0.20/1MOutput Price:Output: $0.50/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Google

No standout differentiators in the data we have for this pair.

xAI
Larger context window (2,000,000 tokens)
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

AI Model Comparison Table
Feature
Google
Gemini 3.1 Pro
xAI
Grok-4.1 Fast Reasoning

FAQ

Common questions about Gemini 3.1 Pro vs Grok-4.1 Fast Reasoning.

Which is better, Gemini 3.1 Pro or Grok-4.1 Fast Reasoning?

Gemini 3.1 Pro (Google) and Grok-4.1 Fast Reasoning (xAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does Gemini 3.1 Pro compare to Grok-4.1 Fast Reasoning in benchmarks?

Gemini 3.1 Pro scores t2-bench: 99.3%, LiveCodeBench Pro: 96.2%, GPQA: 94.3%, MMMLU: 92.6%, BrowseComp: 85.9%.

Is Gemini 3.1 Pro cheaper than Grok-4.1 Fast Reasoning?

Grok-4.1 Fast Reasoning is 12.5x cheaper for input tokens. Gemini 3.1 Pro costs $2.50/M input and $15.00/M output via google. Grok-4.1 Fast Reasoning costs $0.20/M input and $0.50/M output via xai.

What are the context window sizes for Gemini 3.1 Pro and Grok-4.1 Fast Reasoning?

Gemini 3.1 Pro supports 1.0M tokens and Grok-4.1 Fast Reasoning supports 2.0M 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 Grok-4.1 Fast Reasoning?

Key differences include context window (1.0M vs 2.0M), input pricing ($2.50 vs $0.20/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Gemini 3.1 Pro and Grok-4.1 Fast Reasoning?

Gemini 3.1 Pro is developed by Google and Grok-4.1 Fast Reasoning is developed by xAI.

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