GPT-5 Nano vs Mercury 2.5
API pricing, benchmark indices and specs — updated 19 October 2026.
openai · A · API-only
Input / 1M
$0.05
Output / 1M
$0.40
AA index
13
proprietary · 400K context
inception · B · API-only
Input / 1M
$0.04
Output / 1M
$0.15
AA index
12.3
proprietary · 260K context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | GPT-5 Nano | Mercury 2.5 |
|---|---|---|
| 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 | 400,000 | 260,000 |
| 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 | $0.05 | $0.04 |
| API output price / 1M tokens | $0.40 | $0.15 |
| Est. cost per 1M input + 1M output tokens | $0.45 | $0.19 |
| Cached input / 1M tokens | $0.005 | $0.004 |
| AA Intelligence Index | 13 | 12.3 |
| AA Coding Index | — | — |
| AA Agentic Index | — | — |
| Max output tokens | 128,000 | 65,536 |
| API providers | 2 | 1 |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
GPT-5 Nano
$0.45
Mercury 2.5
$0.19
Mercury 2.5 is 2.4× cheaper at list price.