Claude Sonnet 4.5 vs o3
API pricing, benchmark indices and specs — updated 19 October 2026.
anthropic · A · API-only
Input / 1M
$3.00
Output / 1M
$15.00
AA index
20.7
proprietary · 1M context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | Claude Sonnet 4.5 | o3 |
|---|---|---|
| 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 | 1,000,000 | 200,000 |
| 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 | $3.00 | $2.00 |
| API output price / 1M tokens | $15.00 | $8.00 |
| Est. cost per 1M input + 1M output tokens | $18.00 | $10.00 |
| Cached input / 1M tokens | $0.30 | $0.50 |
| AA Intelligence Index | 20.7 | 20.2 |
| AA Coding Index | 52.1 | — |
| AA Agentic Index | 15.8 | — |
| Max output tokens | 64,000 | 100,000 |
| 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 Sonnet 4.5
$18.00
o3
$10.00
o3 is 1.8× cheaper at list price.