GPT-4o mini is cheaper than GPT-5.1-Codex at $0.15/M vs $1.25/M input tokens.
| Spec | GPT-4o mini | GPT-5.1-Codex |
|---|---|---|
| Input price | $0.15/M tokens | $1.25/M tokens |
| Output price | $0.6/M tokens | $10/M tokens |
| Context window | 128K tokens | 400K tokens |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Jul 2024 | Nov 2025 |
Not enough votes to call it. On the specs, GPT-5.1-Codex has the edge: bigger model tier, newer, bigger context window.
GPT-4o mini costs 17x less per token.
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GPT-4o mini is cheaper on both: 8.3× input, 17× output.
Per million tokens. Prices and uptime via OpenRouter, checked 11 Sep 2026.
GPT-4o mini uses 2.1x more hedging