Grok 4.5 vs GPT-5.5
API pricing, benchmark indices and specs — updated 19 October 2026.
x-ai · A · API-only
Input / 1M
$2.00
Output / 1M
$6.00
AA index
38.8
proprietary · 500K context
openai · B · API-only
Input / 1M
$5.00
Output / 1M
$30.00
AA index
38.4
proprietary · 1.0M context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | Grok 4.5 | GPT-5.5 |
|---|---|---|
| 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 | 500,000 | 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 | $2.00 | $5.00 |
| API output price / 1M tokens | $6.00 | $30.00 |
| Est. cost per 1M input + 1M output tokens | $8.00 | $35.00 |
| Cached input / 1M tokens | $0.30 | $0.50 |
| AA Intelligence Index | 38.8 | 38.4 |
| AA Coding Index | 72.4 | 74.9 |
| AA Agentic Index | 41.2 | 36.4 |
| Max output tokens | 450,000 | 128,000 |
| API providers | 1 | 3 |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
Grok 4.5
$8.00
GPT-5.5
$35.00
Grok 4.5 is 4.4× cheaper at list price.