Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's [news post](http://x.ai/news/grok-4-fast). Reaso…
Model details →xAI: Grok 4 Fast vs Anthropic Claude Sonnet Latest
xAI: Grok 4 Fast wins on 3 of 6 axes — pricing and capability skew in its favour for most workloads.
This model always redirects to the latest model in the Anthropic Claude Sonnet family.
Model details →Side-by-side comparison
| Capability | xAI: Grok 4 Fast | Anthropic Claude Sonnet Latest | Winner |
|---|---|---|---|
| Context window Maximum number of input tokens the model can attend to in a single request. | 2M | 1M | 🏆 xAI: Grok 4 Fast |
| Input price (per 1M) Cost per million input tokens billed by the provider. | $0.20 | $2.00 | 🏆 xAI: Grok 4 Fast |
| Output price (per 1M) Cost per million output tokens billed by the provider. | $0.50 | $10.00 | 🏆 xAI: Grok 4 Fast |
| Tool / function calling First-class support for emitting structured tool calls. | Yes | Yes | Tie |
| Vision input Accepts image inputs alongside text. | Yes | Yes | Tie |
| Reasoning mode Internal chain-of-thought / extended-thinking support. | Yes | Yes | Tie |
Frequently asked questions
Is xAI: Grok 4 Fast better than Anthropic Claude Sonnet Latest?
xAI: Grok 4 Fast wins on 3 of 6 axes — pricing and capability skew in its favour for most workloads.
What's the price difference between xAI: Grok 4 Fast and Anthropic Claude Sonnet Latest?
Input: $0.20 vs $2.00 per 1M tokens. Output: $0.50 vs $10.00 per 1M tokens.
What context windows do xAI: Grok 4 Fast and Anthropic Claude Sonnet Latest support?
xAI: Grok 4 Fast supports up to 2M tokens. Anthropic Claude Sonnet Latest supports up to 1M tokens.
Do both xAI: Grok 4 Fast and Anthropic Claude Sonnet Latest support tool calling?
xAI: Grok 4 Fast: yes. Anthropic Claude Sonnet Latest: yes.
Compare xAI: Grok 4 Fast with other models
vs Anthropic Claude Haiku Latestvs Anthropic Claude Sonnet Latestvs Anthropic: Claude Fable Latestvs Anthropic: Claude Opus Latest