xAI
Grok 4 Fast
Fast Grok model for responsive chat, reasoning, and tool-assisted work
Model facts
- Context window
- 2M tokens
- Maximum output
- 64K tokens
- Cheapest paid input
- $0.2 per 1M tokens
- Cheapest paid output
- $0.5 per 1M tokens
- Open weights
- no
- Providers
- 2
Capabilities and modalities
reasoning, tool calling, attachments, temperature control, text, image.
Artificial Analysis benchmarks
Compare this model on the full LLM benchmark leaderboard.
| Configuration | AAI | Coding | Math | Output tokens/s |
|---|---|---|---|---|
| Reasoning | 27.9 | not measured | 89.7 | not measured |
| Non-reasoning | 16.6 | not measured | 41.3 | not measured |
Observed price history
- 2026-08-24: $0.2 input / $0.5 output per 1M tokens
API providers
- Abacus (Non-Reasoning) — model id grok-4-fast-non-reasoning; $0.2 input / $0.5 output per 1M tokens; provider documentation
- ZenMux — model id x-ai/grok-4-fast; $0.2 input / $0.5 output per 1M tokens; provider documentation