Grok 4 Fast vs Gemini 2.5 Pro
Detailed comparison between Grok 4 Fast and Gemini 2.5 Pro for RAG applications. See which LLM best meets your accuracy, performance, and cost needs.
Model Comparison
Grok 4 Fast takes the lead.
Both Grok 4 Fast and Gemini 2.5 Pro are powerful language models designed for RAG applications. However, their performance characteristics differ in important ways.
Why Grok 4 Fast:
- Grok 4 Fast has 228 higher ELO rating
- Grok 4 Fast delivers better overall quality (4.96 vs 4.88)
- Grok 4 Fast is 9.3s faster on average
- Grok 4 Fast has a 24.7% higher win rate
Overview
Key metrics
ELO Rating
Overall ranking quality
Grok 4 Fast
Gemini 2.5 Pro
Win Rate
Head-to-head performance
Grok 4 Fast
Gemini 2.5 Pro
Quality Score
Overall quality metric
Grok 4 Fast
Gemini 2.5 Pro
Average Latency
Response time
Grok 4 Fast
Gemini 2.5 Pro
Visual Performance Analysis
Performance
ELO Rating Comparison
Win/Loss/Tie Breakdown
Quality Across Datasets (Overall Score)
Latency Distribution (ms)
Breakdown
How the models stack up
| Metric | Grok 4 Fast | Gemini 2.5 Pro | Description |
|---|---|---|---|
| Overall Performance | |||
| ELO Rating | 1657 | 1429 | Overall ranking quality based on pairwise comparisons |
| Win Rate | 60.1% | 35.4% | Percentage of comparisons won against other models |
| Quality Score | 4.96 | 4.88 | Average quality across all RAG metrics |
| Pricing & Context | |||
| Input Price per 1M | $0.20 | $1.25 | Cost per million input tokens |
| Output Price per 1M | $0.50 | $10.00 | Cost per million output tokens |
| Context Window | 2000K | 1049K | Maximum context window size |
| Release Date | 2025-09-19 | 2025-06-17 | Model release date |
| Performance Metrics | |||
| Avg Latency | 5.9s | 15.2s | Average response time across all datasets |
Dataset Performance
By benchmark
Comprehensive comparison of RAG quality metrics (correctness, faithfulness, grounding, relevance, completeness) and latency for each benchmark dataset.
MSMARCO
| Metric | Grok 4 Fast | Gemini 2.5 Pro | Description |
|---|---|---|---|
| Quality Metrics | |||
| Correctness | 4.90 | 4.90 | Factual accuracy of responses |
| Faithfulness | 4.90 | 4.93 | Adherence to source material |
| Grounding | 4.90 | 4.93 | Citations and context usage |
| Relevance | 5.00 | 5.00 | Query alignment and focus |
| Completeness | 4.83 | 4.90 | Coverage of all aspects |
| Overall | 4.91 | 4.93 | Average across all metrics |
| Latency Metrics | |||
| Mean | 3894ms | 12449ms | Average response time |
| Min | 1742ms | 7629ms | Fastest response time |
| Max | 6649ms | 23066ms | Slowest response time |
PG
| Metric | Grok 4 Fast | Gemini 2.5 Pro | Description |
|---|---|---|---|
| Quality Metrics | |||
| Correctness | 5.00 | 5.00 | Factual accuracy of responses |
| Faithfulness | 5.00 | 5.00 | Adherence to source material |
| Grounding | 5.00 | 5.00 | Citations and context usage |
| Relevance | 5.00 | 5.00 | Query alignment and focus |
| Completeness | 4.93 | 5.00 | Coverage of all aspects |
| Overall | 4.99 | 5.00 | Average across all metrics |
| Latency Metrics | |||
| Mean | 9142ms | 17834ms | Average response time |
| Min | 4767ms | 11067ms | Fastest response time |
| Max | 17055ms | 49308ms | Slowest response time |
SciFact
| Metric | Grok 4 Fast | Gemini 2.5 Pro | Description |
|---|---|---|---|
| Quality Metrics | |||
| Correctness | 5.00 | 4.73 | Factual accuracy of responses |
| Faithfulness | 5.00 | 4.80 | Adherence to source material |
| Grounding | 5.00 | 4.80 | Citations and context usage |
| Relevance | 5.00 | 4.73 | Query alignment and focus |
| Completeness | 4.83 | 4.57 | Coverage of all aspects |
| Overall | 4.97 | 4.73 | Average across all metrics |
| Latency Metrics | |||
| Mean | 4516ms | 15314ms | Average response time |
| Min | 2358ms | 8817ms | Fastest response time |
| Max | 14942ms | 35365ms | Slowest response time |
Explore More
Compare more LLMs
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