Head to head
OpenAI: GPT-5.6 Luna vs SpaceXAI: Grok 4.5
Live prices, context windows, capabilities, and measured quality — updated continuously.
Side by side
| Metric | OpenAI: GPT-5.6 Luna Openai | SpaceXAI: Grok 4.5 Xai |
|---|---|---|
| Input $/M tokens | $0.200 | $2.00 |
| Output $/M tokens | $1.20 | $6.00 |
| Context window | 1.1M | 500K |
| Max output | 128K | — |
| WM Score | 87 | 85 |
| Benchmark quality | 83.7 | 86.1 |
| Hosts serving it | 3 | 1 |
| Throughput (tok/s) | 99.5 | 52 |
| Latency (ms) | 865 | 900 |
| Vision | ||
| Tools | ||
| Reasoning | ||
| JSON mode |
Which should you pick?
OpenAI: GPT-5.6 Luna costs less per million input tokens — about 10.0× cheaper than SpaceXAI: Grok 4.5. SpaceXAI: Grok 4.5 scores higher on measured quality. OpenAI: GPT-5.6 Luna takes a larger context window, which matters for long documents or big codebases. Prices here are live list prices; the same model can cost less on a different host, so check the model page for the cheapest offering.