Updated March 26, 2026· Based on independent benchmark data
Gemini 3.1 Pro Preview leads in intelligence with a score of 57.2 vs 35.1. Grok 4 Fast (Reasoning) is 10.0x cheaper at $0.20/1M tokens vs $2.00/1M.
| Metric | Grok 4 Fast (Reasoning) | Gemini 3.1 Pro Preview |
|---|---|---|
| Intelligence Score | 35.1 | 57.2 |
| Coding Score | 27.4 | 55.5 |
| Math Score | 89.7 | N/A |
| Speed (tok/s) | 128 tok/s | 113 tok/s |
| Latency (TTFT) | 3.57s | 23.84s |
| Input Price / 1M tokens | $0.20 | $2.00 |
| Output Price / 1M tokens | $0.50 | $12 |
| Context Window | N/A |
Gemini 3.1 Pro Preview outperforms Grok 4 Fast (Reasoning) on the intelligence index with a score of 57.2 compared to 35.1. For coding tasks, Gemini 3.1 Pro Preview has the edge with a coding score of 55.5 vs 27.4.
Both models deliver similar output speeds: Grok 4 Fast (Reasoning) at 128 tok/s and Gemini 3.1 Pro Preview at 113 tok/s. Time to first token is 3.57s for Grok 4 Fast (Reasoning) vs 23.84s for Gemini 3.1 Pro Preview, which affects perceived responsiveness in interactive applications.
Grok 4 Fast (Reasoning) is more affordable at $0.20/1M input tokens ($0.50/1M output), while Gemini 3.1 Pro Preview costs $2.00/1M input ($12/1M output). That makes Gemini 3.1 Pro Preview 10.0x more expensive per token, which can add up significantly at scale. For a typical workload of 100 requests per day at 2,000 tokens each, Grok 4 Fast (Reasoning) would cost approximately $1.20/month vs $12.00/month for Gemini 3.1 Pro Preview in input costs alone.
Choose Grok 4 Fast (Reasoning) when you need lower cost. Choose Gemini 3.1 Pro Preview when you need higher intelligence (57.2), stronger coding performance (55.5).
Gemini 3.1 Pro Preview scores higher on coding benchmarks (55.5 vs 27.4), making it the better choice for programming tasks.
Grok 4 Fast (Reasoning) is cheaper at $0.20/1M input tokens vs $2.00/1M for Gemini 3.1 Pro Preview.
Grok 4 Fast (Reasoning) is faster, producing output at 128 tok/s compared to Gemini 3.1 Pro Preview's 113 tok/s.
No, Grok 4 Fast (Reasoning) does not support image input. However, Gemini 3.1 Pro Preview does support images.
Data last synced: March 26, 2026
| 1.0M |
| Max Output Tokens | N/A | N/A |
| Input Modalities | Text | Audio + File + Image + Text + Video |
| Output Modalities | Text | Text |
| Free Tier | No | No |
It depends on your priorities. Gemini 3.1 Pro Preview scores higher on intelligence (57.2), but Grok 4 Fast (Reasoning) may be better for specific use cases like budget-conscious projects or speed-critical applications.