Updated
Claude Fable 5 vs GPT-5.6 Luna
Claude Fable 5 had 46% fewer counted bugs per line than GPT-5.6 Luna (0.70 vs 1.28).
| Claude Fable 5 | GPT-5.6 Luna | |
|---|---|---|
| Bug rate | ||
| Relative bug rate | 0.70 | 1.28 |
| Rank | #2 of 9 | #7 of 9 |
| Details | ||
| Provider | Anthropic | OpenAI |
| Released | Jun 9, 2026 | Jul 9, 2026 |
| List price | $10 input / $50 output per 1M tokens | $0.20 input / $1.20 output per 1M tokens |
| Share of AI-written code, week of Sep 14 | 0.9% | 1.7% |
1.00 = average · lower is better
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Questions and answers
- Which has fewer bugs, Claude Fable 5 or GPT-5.6 Luna?
- Claude Fable 5 had 46% fewer counted bugs per line than GPT-5.6 Luna (0.70 vs 1.28). Claude Fable 5 ranks #2 of 9 and GPT-5.6 Luna #7.
- Which is cheaper, Claude Fable 5 or GPT-5.6 Luna?
- Claude Fable 5 lists at $10 input / $50 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, Claude Fable 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 0.9% for Claude Fable 5.