Grok 4.1 Fast Reasoning vs Grok 4.20.0309 Reasoning
Grok 4.1 Fast Reasoning vs Grok 4.20.0309 Reasoning: Grok 4.1 Fast Reasoning is cheaper by 92% on average. Grok 4.1 Fast Reasoning from Azure AI Foundry (131,072-token context, reasoning, tool calls) vs. Grok 4.20.0309 Reasoning from xAI (2,000,000-token context, reasoning, tool calls). Use Agent Command Center to A/B both in shadow mode and pick the winner per workload.
Side-by-side cost
Live workload comparison
Same workload run through both models. The cheaper one is highlighted.
3,000
02,000,000
400
0200,000
5,000
01,000,000
At this workload, Grok 4.1 Fast Reasoning is 90% cheaper than Grok 4.20.0309 Reasoning — a savings of $1,157/month ($13,880/year).
Production recipe — Agent Command Center
strategy: cost-optimized
primary:
model: grok-4-1-fast-reasoning
provider: azure-ai-foundry
fallback:
model: grok-4-20-0309-reasoning
provider: xai
shadow: { sample_rate: 0.05 } # mirror 5% of traffic to compare quality live| Grok 4.1 Fast Reasoning | Grok 4.20.0309 Reasoning | |
|---|---|---|
| Input price | $0.200/M | $2.00/M |
| Output price | $0.500/M | $6.00/M |
| Context window | 131,072 | 2,000,000 |
| Max output | 131,072 | 2,000,000 |
| Function calling | ✓ | ✓ |
| Vision | — | ✓ |
| Audio input | — | — |
| Reasoning | ✓ | ✓ |
| Prompt caching | — | — |
| Structured output | ✓ | — |
| Pricing verified | May 12, 2026 | May 12, 2026 |