Updated
Claude Sonnet 5 vs Claude Sonnet 5.5
Claude Sonnet 5.5 had 47% fewer counted bugs per line than Claude Sonnet 5 (0.96 vs 1.80).
| Claude Sonnet 5 | Claude Sonnet 5.5 | |
|---|---|---|
| Bug rate | ||
| Relative bug rate | 1.80 | 0.96 |
| Rank | #8 of 8 | #2 of 8 |
| By coding agent | ||
| Claude Code | 1.81 | 0.92 |
| By bug type | ||
| Logic bugs | 1.67 | 0.74 |
| Testing and docs(statistically tied) | 1.83 | 1.29 |
| By language | ||
| TypeScript | 2.07 | 0.54 |
| Python(statistically tied) | 1.83 | 1.70 |
| Details | ||
| Provider | Anthropic | Anthropic |
| Released | Jun 30, 2026 | Sep 28, 2026 |
| List price | $2 input / $10 output per 1M tokens | $2 input / $10 output per 1M tokens |
| Share of AI-written code, week of Sep 28 | 2.8% | 2.4% |
1.00 = average · lower is better · = statistically tied
More comparisons
Questions and answers
- Which has fewer bugs, Claude Sonnet 5 or Claude Sonnet 5.5?
- Claude Sonnet 5.5 had 47% fewer counted bugs per line than Claude Sonnet 5 (0.96 vs 1.80). Claude Sonnet 5.5 ranks #2 of 8 and Claude Sonnet 5 #8.
- Which is cheaper, Claude Sonnet 5 or Claude Sonnet 5.5?
- Both list at $2 input / $10 output per 1M tokens.
- Does it depend on the programming language?
- In TypeScript, Claude Sonnet 5.5 had the lower rate (0.54 vs 2.07); in Python, they were statistically tied (1.83 and 1.70).
- Does it depend on the kind of bug?
- For logic bugs, Claude Sonnet 5.5 had the lower rate (0.74 vs 1.67); for testing and documentation issues, they were statistically tied (1.83 and 1.29).