Updated
GPT-5.5 vs GPT-5.6 Luna
GPT-5.5 had 64% fewer counted bugs per line than GPT-5.6 Luna (0.47 vs 1.28).
| GPT-5.5 | GPT-5.6 Luna | |
|---|---|---|
| Bug rate | ||
| Relative bug rate | 0.47 | 1.28 |
| Rank | #1 of 9 | #7 of 9 |
| By coding agent | ||
| Codex | 0.42 | 1.32 |
| Details | ||
| Provider | OpenAI | OpenAI |
| Released | Apr 23, 2026 | Jul 9, 2026 |
| List price | $5 input / $30 output per 1M tokens | $0.20 input / $1.20 output per 1M tokens |
| Share of AI-written code, week of Sep 14 | 0.1% | 1.7% |
1.00 = average · lower is better
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Questions and answers
- Which has fewer bugs, GPT-5.5 or GPT-5.6 Luna?
- GPT-5.5 had 64% fewer counted bugs per line than GPT-5.6 Luna (0.47 vs 1.28). GPT-5.5 ranks #1 of 9 and GPT-5.6 Luna #7.
- Which is cheaper, GPT-5.5 or GPT-5.6 Luna?
- GPT-5.5 lists at $5 input / $30 output per 1M tokens; GPT-5.6 Luna lists at $0.20 input / $1.20 output per 1M tokens. GPT-5.6 Luna has the lower list price.
- Which is used more, GPT-5.5 or GPT-5.6 Luna?
- GPT-5.6 Luna, with 1.7% of the AI-written code reviewed by cubic in the week of Sep 14, 2026, against 0.1% for GPT-5.5.