Claude Opus 4.5 vs Claude Sonnet 4.5: what developers actually say
Based on 419 opinions on Hacker News from developers who discussed these two, most of them first-hand users.
Opus 4.5 comes out ahead on quality and autonomy, where both models have data. It has 322 opinions from 259 authors and 78% approval, with a 120-to-28 code-quality split and a 30-to-4 autonomy split; Sonnet 4.5 has 97 opinions, 57% approval, code quality near even at 22 to 21, and reliability at 5 positive to 10 negative. Six explicit comparisons favored Opus, none favored Sonnet, and Opus also shows 15 positive speed mentions and zero negative ones. Sonnet is the better pick for cheaper, closely supervised work on familiar patterns; Opus for long autonomous runs on large codebases.
When developers explicitly said they prefer one or switched: 6 picked Claude Opus 4.5, 0 picked Claude Sonnet 4.5.
Choose Claude Opus 4.5 if
- Need long autonomous runs on complex work
- Work in large codebases and want stronger quality signals
- Can absorb a higher cost for stronger output
Choose Claude Sonnet 4.5 if
- Want a cheaper option for routine coding
- Keep a human in the loop on familiar patterns
- Need spec-driven work with tight review
Where each one wins and loses
Why developers switched
Picked Claude Opus 4.5
Picked Claude Sonnet 4.5
No explicit switches recorded.
Summaries are paraphrased. Each links to the original comment.
Side by side
| Claude Opus 4.5 | Claude Sonnet 4.5 | |
|---|---|---|
| Approval | 78% | 57% |
| Last 90 days | 90% | – |
| Opinions | 322 | 97 |
| First-hand users | 254 | 93 |