Model Comparison
Gemini 2.5 Pro Preview 06-05 vs Grok 4 FastWhich is better in 2026?
Grok 4 Fast has a slight edge in benchmark performance. Grok 4 Fast is 12.5x cheaper per token.
Verdict: Gemini 2.5 Pro Preview 06-05 vs Grok 4 Fast — which is better?
Gemini 2.5 Pro Preview 06-05 (by Google) and Grok 4 Fast (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.
Gemini 2.5 Pro Preview 06-05 outperforms in 2 benchmarks (GPQA, Humanity's Last Exam), while Grok 4 Fast is better at 3 benchmarks (AIME 2025, LiveCodeBench, SimpleQA). Grok 4 Fast has a slight edge in benchmark performance.
On price, Grok 4 Fast is roughly 12.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok 4 Fast also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Gemini 2.5 Pro Preview 06-05 if…
- you want predictable pricing at $1.25/M input and $10.00/M output
Choose Grok 4 Fast if…
- you want the strongest raw capability — it leads on 3 of 5 shared benchmarks
- cost matters — it's about 12.5x cheaper per token
- you process long inputs — it offers a 2,000,000 token context window
- you want the most recent training data — it shipped Aug 2025
Performance Benchmarks
Comparative analysis across standard metrics
Gemini 2.5 Pro Preview 06-05 outperforms in 2 benchmarks (GPQA, Humanity's Last Exam), while Grok 4 Fast is better at 3 benchmarks (AIME 2025, LiveCodeBench, SimpleQA).
Grok 4 Fast has a slight edge in benchmark performance.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 2.5 Pro Preview 06-05 ($1.25/1M tokens) is 6.3x more expensive than Grok 4 Fast ($0.20/1M tokens).
For output processing, Gemini 2.5 Pro Preview 06-05 ($10.00/1M tokens) is 20.0x more expensive than Grok 4 Fast ($0.50/1M tokens).
In conclusion, Gemini 2.5 Pro Preview 06-05 is more expensive than Grok 4 Fast.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Grok 4 Fast accepts 2,000,000 input tokens compared to Gemini 2.5 Pro Preview 06-05's 1,048,576 tokens. Gemini 2.5 Pro Preview 06-05 can generate longer responses up to 65,535 tokens, while Grok 4 Fast is limited to 30,000 tokens.
Input Capabilities
Supported data types and modalities
Both Gemini 2.5 Pro Preview 06-05 and Grok 4 Fast support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 2.5 Pro Preview 06-05
Grok 4 Fast
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Gemini 2.5 Pro Preview 06-05 was released on 2025-06-05, while Grok 4 Fast was released on 2025-08-28.
Grok 4 Fast is 3 months newer than Gemini 2.5 Pro Preview 06-05.
Jun 5, 2025
1.1 years ago
Aug 28, 2025
10 months ago
2mo newerKnowledge Cutoff
When training data ends
Gemini 2.5 Pro Preview 06-05 has a documented knowledge cutoff of 2025-01-31, while Grok 4 Fast's cutoff date is not specified.
We can confirm Gemini 2.5 Pro Preview 06-05's training data extends to 2025-01-31, but cannot make a direct comparison without Grok 4 Fast's cutoff date.
Jan 2025
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Provider Availability
Gemini 2.5 Pro Preview 06-05 is available from Google. Grok 4 Fast is available from xAI.
Gemini 2.5 Pro Preview 06-05
Grok 4 Fast
Outputs Comparison
Key Takeaways
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Gemini 2.5 Pro Preview 06-05 and Grok 4 Fast side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Gemini 2.5 Pro Preview 06-05 vs Grok 4 Fast.