o3 Pro vs GPT-5.5 Pro
API pricing, benchmark indices and specs — updated 19 October 2026.
openai · A · API-only
Input / 1M
$20.00
Output / 1M
$80.00
AA index
21.9
proprietary · 200K context
openai · B · API-only
Input / 1M
$30.00
Output / 1M
$180.00
AA index
—
proprietary · 1.0M context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | o3 Pro | GPT-5.5 Pro |
|---|---|---|
| Deployment | API-only (closed weights) | API-only (closed weights) |
| Parameters | n/a — API-only | n/a — API-only |
| Architecture | n/a — API-only | n/a — API-only |
| Context length | 200,000 | 1,050,000 |
| Licence | Proprietary | Proprietary |
| Commercial use | Per API terms | Per API terms |
| Languages | n/a — API-only | n/a — API-only |
| Downloads 30d | n/a — API-only | n/a — API-only |
| Downloads all time | n/a — API-only | n/a — API-only |
| Quantizations on the Hub | n/a — API-only | n/a — API-only |
| Gated | n/a — API-only | n/a — API-only |
| First seen on the Hub | n/a — API-only | n/a — API-only |
| API input price / 1M tokens | $20.00 | $30.00 |
| API output price / 1M tokens | $80.00 | $180.00 |
| Est. cost per 1M input + 1M output tokens | $100.00 | $210.00 |
| Cached input / 1M tokens | — | — |
| AA Intelligence Index | 21.9 | — |
| AA Coding Index | — | — |
| AA Agentic Index | — | — |
| Max output tokens | 100,000 | 128,000 |
| API providers | 1 | 1 |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
o3 Pro
$100.00
GPT-5.5 Pro
$210.00
o3 Pro is 2.1× cheaper at list price.