Head to head
OpenAI: GPT-5.5 vs SpaceXAI: Grok 4.5
Live prices, context windows, capabilities, and measured quality — updated continuously.
Side by side
| Metric | OpenAI: GPT-5.5 Openai | SpaceXAI: Grok 4.5 Xai |
|---|---|---|
| Input $/M tokens | $5.00 | $2.00 |
| Output $/M tokens | $30.00 | $6.00 |
| Context window | 1.1M | 500K |
| Max output | 128K | — |
| WM Score | 84 | 84 |
| Benchmark quality | 86.1 | 86.1 |
| Hosts serving it | 3 | 1 |
| Throughput (tok/s) | 25 | 53 |
| Latency (ms) | 1535 | 1193 |
| Vision | ||
| Tools | ||
| Reasoning | ||
| JSON mode |
Which should you pick?
SpaceXAI: Grok 4.5 costs less per million input tokens — about 2.5× cheaper than OpenAI: GPT-5.5. OpenAI: GPT-5.5 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.