xAI: Grok 4 Fast

xAI: Grok 4 Fast is a large language model API from xAI, part of its Grok 4 model family. At $0.200 per million input tokens and $0.500 per million output tokens, it sits in the budget tier — among the cheaper options for high-throughput or cost-sensitive workloads. Output tokens cost about 3× as much as input, so prompt-heavy workloads run noticeably cheaper than generation-heavy ones. An exceptionally large 2M-token context window (≈3,000 pages of text) means entire repositories or document collections can be processed without chunking. Beyond plain text it also accepts Image, File input, so it can be applied to multimodal tasks rather than text alone. On Artificial Analysis's Intelligence Index it scores 27 (C grade), a useful proxy for its general reasoning strength relative to the other models tracked here. All prices on this page reflect OpenRouter's routed rates and are re-synced automatically every day; confirm against the provider's official pricing before committing to production.

• xAI: Grok 4 Fast Input price: $0.2/M tokens
• xAI: Grok 4 Fast Output price: $0.5/M tokens
• Context window: 2,000,000 tokens
• Provider: xAI
• Model family: Grok 4
• Modalities: Text, Image, File
• Data source: OpenRouter, updated daily