GPT-5.6 Terra vs GPT-5.6 Luna Codex credit cost
On a daily-coding request, GPT-5.6 Terra costs about 1 Codex credits ($0.04) versus 0.4 credits ($0.02) for GPT-5.6 Luna, so GPT-5.6 Terra costs about 2.5x as much. Both meter at $0.04 per credit, i.e. exact OpenAI API rates. Verified 2026-07-21.
| GPT-5.6 Terra | GPT-5.6 Luna | |
|---|---|---|
| Input, credits / 1M | 62.5 | 25 |
| Output, credits / 1M | 375 | 150 |
| API rate in / out, $ / 1M | $2.50 / $15.00 | $1.00 / $6.00 |
| Daily-coding request | 1 cr ($0.04) | 0.4 cr ($0.02) |