Grok 4 Fast vs Sonar Reasoning Pro
xAI vs Perplexity — benchmarks, pricing, and capabilities side by side.
- •Sonar Reasoning Pro has the higher intelligence index (95.7 vs 78.7)
- •Grok 4 Fast is cheaper ($0.20 vs $2.00 per 1M input)
- •Grok 4 Fast has a larger context window (2M)
| Grok 4 Fast | Sonar Reasoning Pro | |
|---|---|---|
| Intelligence index | 78.7 | 95.7 |
| Developer | xAI | Perplexity |
| Type | LLM | Multimodal |
| Access | API only | API only |
| Context window | 2,000,000 tokens | 128,000 tokens |
| Input price | $0.20 / 1M | $2.00 / 1M |
| Output price | $0.50 / 1M | $8.00 / 1M |
| Speed | 90 tok/s | — |
| Released | September 19, 2025 | March 7, 2025 |
| Parameters | — | — |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |