Grok 3 Mini vs Grok 4 Fast
Detailed pricing comparison and cost analysis.
Updated March 2026
Cost Simulator
| Feature | Grok 3 Mini | Grok 4 Fast |
|---|---|---|
| Provider | xAI | xAI |
| Input Price (1M) | $0.30 | $0.20 |
| Output Price (1M) | $0.50 | $0.50 |
| Context Window | 131,000 | 2,000,000 |
Verdict
Grok 3 Mini costs $0.30 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 Fast is 33% cheaper on input tokens than Grok 3 Mini. For output tokens, Grok 3 Mini is the more affordable option at $0.50/1M vs $0.50.
On context window, Grok 4 Fast supports 2,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose Grok 3 Mini
- ✓ You are already integrated with xAI
When to choose Grok 4 Fast
- ✓ You need the lowest input token cost ($ 0.20/1M)
- ✓ You need a larger context window (2,000,000 tokens)
- ✓ 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.