Claude Opus 4.5 vs GPT-5.2-Codex
API pricing, benchmark indices and specs — updated 19 October 2026.
anthropic · A · API-only
Input / 1M
$5.00
Output / 1M
$25.00
AA index
29.1
proprietary · 200K context
openai · B · API-only
Input / 1M
$1.75
Output / 1M
$14.00
AA index
28.5
proprietary · 400K context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | Claude Opus 4.5 | GPT-5.2-Codex |
|---|---|---|
| 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 | 400,000 |
| 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 | $5.00 | $1.75 |
| API output price / 1M tokens | $25.00 | $14.00 |
| Est. cost per 1M input + 1M output tokens | $30.00 | $15.75 |
| Cached input / 1M tokens | $0.50 | $0.18 |
| AA Intelligence Index | 29.1 | 28.5 |
| AA Coding Index | — | — |
| AA Agentic Index | — | — |
| Max output tokens | 64,000 | 128,000 |
| API providers | 5 | 1 |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
Claude Opus 4.5
$30.00
GPT-5.2-Codex
$15.75
GPT-5.2-Codex is 1.9× cheaper at list price.