Updated
Claude Opus 5.5 vs Claude Sonnet 5.5
Claude Sonnet 5.5 had 41% fewer counted bugs per line than Claude Opus 5.5 (0.96 vs 1.63).
| Claude Opus 5.5 | Claude Sonnet 5.5 | |
|---|---|---|
| Bug rate | ||
| Relative bug rate | 1.63 | 0.96 |
| Rank | #7 of 8 | #2 of 8 |
| By coding agent | ||
| Claude Code | 1.63 | 0.92 |
| By bug type | ||
| Logic bugs | 1.40 | 0.74 |
| Testing and docs | 2.43 | 1.29 |
| By language | ||
| TypeScript | 1.62 | 0.54 |
| Python(statistically tied) | 1.17 | 1.70 |
| Details | ||
| Provider | Anthropic | Anthropic |
| Released | Sep 22, 2026 | Sep 28, 2026 |
| List price | $4 input / $20 output per 1M tokens | $2 input / $10 output per 1M tokens |
| Share of AI-written code, week of Sep 28 | 56.4% | 2.4% |
1.00 = average · lower is better · = statistically tied
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Questions and answers
- Which has fewer bugs, Claude Opus 5.5 or Claude Sonnet 5.5?
- Claude Sonnet 5.5 had 41% fewer counted bugs per line than Claude Opus 5.5 (0.96 vs 1.63). Claude Sonnet 5.5 ranks #2 of 8 and Claude Opus 5.5 #7.
- Which is cheaper, Claude Opus 5.5 or Claude Sonnet 5.5?
- Claude Opus 5.5 lists at $4 input / $20 output per 1M tokens; Claude Sonnet 5.5 lists at $2 input / $10 output per 1M tokens. Claude Sonnet 5.5 has the lower list price.
- Does it depend on the programming language?
- In TypeScript, Claude Sonnet 5.5 had the lower rate (0.54 vs 1.62); in Python, they were statistically tied (1.17 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 1.40); for testing and documentation issues, Claude Sonnet 5.5 had the lower rate (1.29 vs 2.43).