Grok 4.1 Fast vs Grok 4 Fast
Detailed pricing comparison and cost analysis.
Updated April 2026
Cost Simulator
| Feature | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| Provider | xAI | xAI |
| Input Price (1M) | $0.20 | $0.20 |
| Output Price (1M) | $0.50 | $0.50 |
| Context Window | 2,000,000 | 2,000,000 |
Verdict
Grok 4.1 Fast costs $0.20 per 1M input tokens and $0.50 per 1M output tokens. Grok 4 Fast costs $0.20 per 1M input tokens and $0.50 per 1M output tokens. Grok 4.1 Fast and Grok 4 Fast have identical input token pricing. For output tokens, Grok 4.1 Fast is the more affordable option at $0.50/1M vs $0.50.
On context window, Grok 4.1 Fast supports 2,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose Grok 4.1 Fast
- ✓ You are already integrated with xAI
When to choose Grok 4 Fast
- ✓ You are already integrated with xAI
Use the calculator above to simulate your specific workload and find the exact break-even point. For most applications, the cheapest model is the one that minimises your total monthly bill given your input-to-output token ratio.
Frequently Asked Questions
Is Grok 4.1 Fast cheaper than Grok 4 Fast? ▼
Grok 4.1 Fast and Grok 4 Fast have identical input token pricing at $0.20/1M tokens.
What is the context window of Grok 4.1 Fast vs Grok 4 Fast? ▼
Grok 4.1 Fast has a 2,000,000-token context window. Grok 4 Fast has a 2,000,000-token context window. Grok 4.1 Fast supports the larger context, suitable for longer documents and agentic workflows.
Which model is better: Grok 4.1 Fast or Grok 4 Fast? ▼
The best choice depends on your use case. For cost efficiency on input tokens, Grok 4.1 Fast is the cheaper option. For maximum context length, Grok 4.1 Fast supports 2,000,000 tokens. Use the comparison table above to find the right fit for your workload.