Grok 4.20 Beta vs Grok 4 Fast
Detailed pricing comparison and cost analysis.
Updated March 2026
Cost Simulator
| Feature | Grok 4.20 Beta | Grok 4 Fast |
|---|---|---|
| Provider | xAI | xAI |
| Input Price (1M) | $2.00 | $0.20 |
| Output Price (1M) | $6.00 | $0.50 |
| Context Window | 2,000,000 | 2,000,000 |
Verdict
Grok 4.20 Beta costs $2.00 per 1M input tokens and $6.00 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 90% cheaper on input tokens than Grok 4.20 Beta. For output tokens, Grok 4 Fast is the more affordable option at $0.50/1M vs $6.00.
On context window, Grok 4.20 Beta supports 2,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose Grok 4.20 Beta
- ✓ You are already integrated with xAI
When to choose Grok 4 Fast
- ✓ You need the lowest input token cost ($ 0.20/1M)
- ✓ Your workload is output-heavy — Grok 4 Fast generates text cheaper
- ✓ 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.