Grok 4.5 vs grok-4-fast-reasoning
| xAI Grok 4.5 | xAI grok-4-fast-reasoning | |
|---|---|---|
| Vendor | xAI | xAI |
| Context window | 500,000 | 2,097,152 |
| Max output | 2,000,000 | 30,000 |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| File input | Yes | Yes |
| Input | text, image | text, image |
| Output | text | text |
| Released | 2026-07-08 | 2025-08-27 |