GPT-5.3-Codex vs Claude Sonnet 4.6
API pricing, benchmark indices and specs — updated 19 October 2026.
openai · A · API-only
Input / 1M
$1.75
Output / 1M
$14.00
AA index
32.5
proprietary · 400K context
anthropic · B · API-only
Input / 1M
$3.00
Output / 1M
$15.00
AA index
30.1
proprietary · 1M context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | GPT-5.3-Codex | Claude Sonnet 4.6 |
|---|---|---|
| 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 | 400,000 | 1,000,000 |
| 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 | $1.75 | $3.00 |
| API output price / 1M tokens | $14.00 | $15.00 |
| Est. cost per 1M input + 1M output tokens | $15.75 | $18.00 |
| Cached input / 1M tokens | $0.18 | $0.30 |
| AA Intelligence Index | 32.5 | 30.1 |
| AA Coding Index | — | 63 |
| AA Agentic Index | — | 31.8 |
| Max output tokens | 128,000 | 128,000 |
| API providers | 2 | 5 |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
GPT-5.3-Codex
$15.75
Claude Sonnet 4.6
$18.00
GPT-5.3-Codex is 1.1× cheaper at list price.