Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | GPT-5.6 Luna (medium) | Grok 4.5 (high) |
|---|---|---|
| Input ($/M tokens) | $1 | $2 |
| Output ($/M tokens) | $6 | $6 |
Data from Artificial Analysis API — 12 benchmarks
GPT-5.6 Luna (medium) is cheaper overall. Its blended price (3:1 input/output ratio) is $2.25/M tokens vs $3.00/M for Grok 4.5 (high).
Grok 4.5 (high) wins 5 out of 12 benchmarks compared to 0 for GPT-5.6 Luna (medium). See the detailed benchmark chart above for per-category results.
GPT-5.6 Luna (medium) generates tokens faster at 223 tok/s vs 120 tok/s. GPT-5.6 Luna (medium) also has lower time-to-first-token (1.40s vs 16.24s).
Choose based on your priorities: GPT-5.6 Luna (medium) for lower cost, Grok 4.5 (high) for stronger benchmark performance, and GPT-5.6 Luna (medium) for faster generation. For latency-sensitive apps, check the TTFT comparison above.