Head to head
Claude Opus 5.5 vs GPT-6.1 Sol
Which is better, Claude Opus 5.5 or GPT-6.1 Sol?
Claude Opus 5.5 finishes ahead of GPT-6.1 Sol on the index, 92.8 to 90.3. It is the stronger of the two on Craft, while GPT-6.1 Sol still leads on 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.
GPT-6.1 Sol
04 of 73
90.3
Near-Astra answers at a fifth of the price. The OpenAI model most teams should deploy now.
The four scores, side by side
| Score | Claude Opus 5.5 | GPT-6.1 Sol | Difference |
|---|---|---|---|
| Craft | 98 | 92 | +6 |
| Speed | 84 | 82 | +2 |
| Control | 91 | 91 | — |
| Value | 84 | 89 | +5 |
| Index score | 92.8 | 90.3 | +2.5 |
Which to pick
Pick Claude Opus 5.5 unless Value is what decides it for you, which is exactly where GPT-6.1 Sol is the better answer.
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
GPT-6.1 Sol
GPT-6.1 Sol launched at DevDay a week after GPT-6 Sol and replaces it at the same price. OpenAI describes it as near-Astra performance at a lower cost, and the leaderboards bear that out: it scores just below Astra on the Artificial Analysis index and well above it with human voters. At two dollars in and ten out, it is priced head to head with Claude Sonnet 5.5, and it is the default choice inside the OpenAI ecosystem.
Where it shines
- Close to Astra on benchmarks for a fifth of the price
- Preferred over Astra by human voters
- Every framework and agent toolkit supports it from day one