GPT-3.5 Turbo 16k vs GPT-5.1-Codex-Max
API pricing, benchmark indices and specs — updated 19 October 2026.
openai · A · API-only
Input / 1M
$3.00
Output / 1M
$4.00
AA index
—
proprietary · 16.4K context
openai · B · API-only
Input / 1M
$1.25
Output / 1M
$10.00
AA index
—
proprietary · 400K context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | GPT-3.5 Turbo 16k | GPT-5.1-Codex-Max |
|---|---|---|
| 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 | 16,385 | 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 | $3.00 | $1.25 |
| API output price / 1M tokens | $4.00 | $10.00 |
| Est. cost per 1M input + 1M output tokens | $7.00 | $11.25 |
| Cached input / 1M tokens | — | $0.13 |
| AA Intelligence Index | — | — |
| AA Coding Index | — | — |
| AA Agentic Index | — | — |
| Max output tokens | 4,096 | 128,000 |
| API providers | 2 | 1 |
| Tool calling | Yes | Yes |
| Reasoning mode | No | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
GPT-3.5 Turbo 16k
$7.00
GPT-5.1-Codex-Max
$11.25
GPT-3.5 Turbo 16k is 1.6× cheaper at list price.