What is a Codex credit
A Codex credit is a fixed dollar amount: $0.04. OpenAI meters Codex usage in credits rather than dollars, but the credit rate card is not a separate pricing decision. It is the direct API dollar rate card, multiplied by a constant factor, for every model.
The constant factor
Dividing the direct API dollar rate by $0.04 gives the credit rate, for input tokens, cached input tokens, and output tokens alike. Equivalently, the credit rate card is the API dollar card multiplied by 25. That factor is the same for every model OpenAI prices this way, which is what makes it a repackaging rather than a per-model markup.
Worked example: GPT-5.6 Terra
| Token type | Credits / 1M | x $0.04 | Direct API / 1M |
|---|---|---|---|
| Input | 62.5 | $2.50 | $2.50 |
| Cached input | 6.25 | $0.25 | $0.25 |
| Output | 375 | $15.00 | $15.00 |
The third and fourth columns match on every row: that is the proof, not an assertion. See the full GPT-5.6 Terra page for the same check across a whole request.