GPT-4.5 is OpenAI largest and most expensive model, positioned as a research-grade system with the deepest world knowledge. At $75/$150 per MTok, it is significantly more expensive than other models but excels at tasks requiring broad knowledge, nuanced understanding, and reduced hallucination. It is best suited for high-stakes applications where accuracy is paramount.
| Benchmark | Score |
|---|---|
| Arena Elo (LMArena) | 1394 |
| Context Window | 128K |
| Price (input/output) | $75/$150 |
Listed in the OpenRouter catalog in our daily snapshots since Jun 19, 2026 (31 snapshots). Per-MTok pricing has not been captured for this listing yet; this section fills in as priced snapshots accumulate.