Head to head
Claude Opus 5 vs Claude Sonnet 5
Which is better, Claude Opus 5 or Claude Sonnet 5?
Claude Opus 5 finishes ahead of Claude Sonnet 5 on the index, 87.1 to 82.5. It is the stronger of the two on Craft, while Claude Sonnet 5 still leads on Speed. Both are scored on the same rubric, in the same week, and neither placing is sponsored.
Updated
Claude Opus 5
12 of 73
87.1
The default of the summer, now replaced by an Opus that is cheaper and better.
Claude Sonnet 5
33 of 73
82.5
Sonnet 5.5 costs exactly the same and is far stronger. There is little reason to stay.
The four scores, side by side
| Score | Claude Opus 5 | Claude Sonnet 5 | Difference |
|---|---|---|---|
| Craft | 92 | 82 | +10 |
| Speed | 82 | 88 | +6 |
| Control | 90 | 89 | +1 |
| Value | 74 | 76 | +2 |
| Index score | 87.1 | 82.5 | +4.6 |
Which to pick
Pick Claude Opus 5 unless Speed is what decides it for you, which is exactly where Claude Sonnet 5 is the better answer.
Claude Opus 5
Opus 5 was the model to reach for by default from July, and it is still strong on serious coding and agent work. Opus 5.5 has now replaced it at a lower price per token with clearly better results on both independent leaderboards, and Anthropic lists Opus 5 as a legacy model. There is no reason to start new work on it, though nothing forces existing work to move yet.
Where it shines
- Frontier-class output on coding and agent work
- Fast enough for interactive use
- Excellent at long-context reading of an existing codebase
Claude Sonnet 5
Sonnet 5 was the coding workhorse of the summer, and it still applies patches that compile and holds up over long tool-calling chains. Sonnet 5.5 now costs exactly the same per token and scores far higher on the Artificial Analysis index, so the only reason to stay is a pipeline you have tuned carefully and do not want to re-test. Anthropic lists it as a legacy model.
Where it shines
- Reliable tool calling over long chains
- Follows a repository's existing conventions
- Well understood after months of heavy production use