GPT-5.6 Luna vs Grok 4 Fast
Grok 4 Fast is cheaper on output tokens, while Grok 4 Fast offers a larger context window. Choose GPT-5.6 Luna or Grok 4 Fast based on the trade-off between cost, context, and the benchmarks that matter for your use case.
| Spec | GPT-5.6 Luna | Grok 4 Fast |
|---|---|---|
| Provider | ZenMux | ZenMux |
| Input / 1M tokens | $1.00 | $0.20 |
| Output / 1M tokens | $6.00 | $0.50 |
| Context window | 1.1M | 2M |
| Parameters | — | — |
| Open weights | No | No |
| Released | Jul 2026 | Sep 2025 |
FAQ
Pricing is indicative — confirm with the provider before production use. Highlighted values indicate the better figure for that row.