Gemini 3.1 Pro vs Grok 4 Fast Comparison

Comparing Gemini 3.1 Pro and Grok 4 Fast across benchmarks, pricing, and capabilities.

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Performance Benchmarks

Comparative analysis across standard metrics

3 benchmarks

Gemini 3.1 Pro outperforms in 3 benchmarks (BrowseComp, GPQA, Humanity's Last Exam), while Grok 4 Fast is better at 0 benchmarks.

Gemini 3.1 Pro significantly outperforms across most benchmarks.

Tue Mar 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok 4 Fast costs less

For input processing, Gemini 3.1 Pro ($2.50/1M tokens) is 12.5x more expensive than Grok 4 Fast ($0.20/1M tokens).

For output processing, Gemini 3.1 Pro ($15.00/1M tokens) is 30.0x more expensive than Grok 4 Fast ($0.50/1M tokens).

In conclusion, Gemini 3.1 Pro is more expensive than Grok 4 Fast.*

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

Lowest available price from all providers

Tue Mar 17 2026 • llm-stats.com

Gemini 3.1 Pro

Input tokens$2.50

Output tokens$15.00

Best providerGoogle

Grok 4 Fast

Input tokens$0.20

Output tokens$0.50

Best providerxAI

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Context Window

Maximum input and output token capacity

Grok 4 Fast 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 Fast is limited to 30,000 tokens.

Gemini 3.1 Pro

Input1,048,576 tokens

Output65,536 tokens

Grok 4 Fast

Input2,000,000 tokens

Output30,000 tokens

Tue Mar 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Gemini 3.1 Pro and Grok 4 Fast 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 Fast

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 Fast

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 3.1 Pro was released on 2026-02-19, while Grok 4 Fast was released on 2025-08-28.

Gemini 3.1 Pro is 6 months newer than Grok 4 Fast.

Gemini 3.1 Pro

Feb 19, 2026

3 weeks ago

5mo newer

Grok 4 Fast

Aug 28, 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 Fast'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 Fast's cutoff date.

Gemini 3.1 Pro

Jan 2025

Grok 4 Fast

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Provider Availability

Gemini 3.1 Pro is available from Google. Grok 4 Fast is available from xAI. The availability of providers can affect quality of the model and reliability.