Model Comparison

Gemini 3.1 Pro vs Grok 4 Fast

Gemini 3.1 Pro significantly outperforms across most benchmarks. Grok 4 Fast is 20.5x 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, GPQA, Humanity's Last Exam), while Grok 4 Fast is better at 0 benchmarks.

Gemini 3.1 Pro significantly outperforms across most benchmarks.

Tue Apr 14 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 Apr 14 2026 • llm-stats.com
Google
Gemini 3.1 Pro
Input tokens$2.50
Output tokens$15.00
Best providerGoogle
xAI
Grok 4 Fast
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 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.

Google
Gemini 3.1 Pro
Input1,048,576 tokens
Output65,536 tokens
xAI
Grok 4 Fast
Input2,000,000 tokens
Output30,000 tokens
Tue Apr 14 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

1 months ago

5mo newer
Grok 4 Fast

Aug 28, 2025

7 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

—

Provider Availability

Gemini 3.1 Pro is available from Google. Grok 4 Fast is available from xAI.

Gemini 3.1 Pro

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

Grok 4 Fast

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

Outputs Comparison

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Key Takeaways

Google
Higher BrowseComp score (85.9% vs 44.9%)
Higher GPQA score (94.3% vs 85.7%)
Higher Humanity's Last Exam score (51.4% vs 20.0%)
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 Fast

FAQ

Common questions about Gemini 3.1 Pro vs Grok 4 Fast

Gemini 3.1 Pro significantly outperforms across most benchmarks. Gemini 3.1 Pro is made by Google and Grok 4 Fast is made by xAI. 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%. Grok 4 Fast scores SimpleQA: 95.0%, HMMT 2025: 93.3%, AIME 2025: 92.0%, GPQA: 85.7%, LiveCodeBench: 80.0%.
Grok 4 Fast 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 Fast costs $0.20/M input and $0.50/M output via xai.
Gemini 3.1 Pro supports 1.0M tokens and Grok 4 Fast supports 2.0M 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 2.0M), input pricing ($2.50 vs $0.20/M). See the full comparison above for benchmark-by-benchmark results.
Gemini 3.1 Pro is developed by Google and Grok 4 Fast is developed by xAI.