Updated
Claude Fable 5.1 vs GPT-6 Luna
GPT-6 Luna had 58% fewer counted bugs per line than Claude Fable 5.1 (0.45 vs 1.07).
| Claude Fable 5.1 | GPT-6 Luna | |
|---|---|---|
| Bug rate | ||
| Relative bug rate | 1.07 | 0.45 |
| Rank | #3 of 7 | #1 of 7 |
| By language | ||
| TypeScript | 1.24 | 0.73 |
| Details | ||
| Provider | Anthropic | OpenAI |
| Released | Sep 1, 2026 | Sep 22, 2026 |
| List price | $10 input / $50 output per 1M tokens | $0.10 input / $0.50 output per 1M tokens |
| Share of AI-written code, week of Oct 12 | 3.4% | 1.4% |
1.00 = average · lower is better
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Questions and answers
- Which has fewer bugs, Claude Fable 5.1 or GPT-6 Luna?
- GPT-6 Luna had 58% fewer counted bugs per line than Claude Fable 5.1 (0.45 vs 1.07). GPT-6 Luna ranks #1 of 7 and Claude Fable 5.1 #3.
- Which is cheaper, Claude Fable 5.1 or GPT-6 Luna?
- Claude Fable 5.1 lists at $10 input / $50 output per 1M tokens; GPT-6 Luna lists at $0.10 input / $0.50 output per 1M tokens. GPT-6 Luna has the lower list price.
- Does it depend on the programming language?
- In TypeScript, GPT-6 Luna had the lower rate (0.73 vs 1.24).
- Which is used more, Claude Fable 5.1 or GPT-6 Luna?
- Claude Fable 5.1, with 3.4% of the AI-written code reviewed by cubic in the week of Oct 12, 2026, against 1.4% for GPT-6 Luna.