GPT-5.5 vs GPT-5.4
30-second takeaway
- GPT-5.4 has the cheaper input: $2.5 vs $5 (per 1M tokens, 50% less)
- Same context window (1.05M tokens)
More specs (max output / capabilities)
| max output | 128,000 | 128,000 |
| Reasoning | ✓ Yes | ✓ Yes |
| Tool calls | ✓ Yes | ✓ Yes |
| Open weights | — No | — No |
Prices are official/data-source rates (per 1M tokens), not what relays actually charge — relay prices vary with discounts and group multipliers. See methodology.