Head to head
Claude Opus 5.5 vs Claude Opus 5
Which is better, Claude Opus 5.5 or Claude Opus 5?
Claude Opus 5.5 finishes ahead of Claude Opus 5 on the index, 92.8 to 87.1, and leads on all four scores: craft, speed, control and value. Both are scored on the same rubric, in the same week, and neither placing is sponsored.
Updated
Claude Opus 5.5
01 of 73
92.8
Fable-level answers for less than the Opus it replaces. The new default.
Claude Opus 5
12 of 73
87.1
The default of the summer, now replaced by an Opus that is cheaper and better.
The four scores, side by side
| Score | Claude Opus 5.5 | Claude Opus 5 | Difference |
|---|---|---|---|
| Craft | 98 | 92 | +6 |
| Speed | 84 | 82 | +2 |
| Control | 91 | 90 | +1 |
| Value | 84 | 74 | +10 |
| Index score | 92.8 | 87.1 | +5.7 |
Which to pick
Claude Opus 5.5 is the safer pick on every axis we score. Claude Opus 5 earns its place in the index, but nothing in these four numbers argues for it over Claude Opus 5.5.
Claude Opus 5.5
Opus 5.5 reset the top of this index. Anthropic says it performs at the level of Fable 5.1 while costing less than Opus 5, and the independent leaderboards agree: it tops the Artificial Analysis index and sits second on the human-preference arena. It keeps the million-token window and runs long agent loops without drifting. If you want one paid model and no further decisions this quarter, this is it.
Where it shines
- Highest score on the Artificial Analysis index as of October 2026
- Matches the Fable tier on long agentic work at under half its price
- A fast mode for interactive work, in research preview
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