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Whats_AI: Claude Opus 5.5 tops writing benchmark with 2631 Elo, 307-point lead over second place
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An X post from the account 'Whats_AI' reports that Claude Opus 5.5 achieved a score of 2631 Elo on a writing benchmark, surpassing the second-place model Fable at 2324 Elo by a 307-point gap. The post describes this as the largest single jump recorded since the benchmark began in June 2026, and notes that Opus 5.5 is the first model to clear 91 out of 100 on the rubric. However, the post also notes that at maximum effort, the model takes 17 minutes and costs $3.43 to write one script, making it the slowest configuration on the board by far and among the top five most expensive. The author states the performance 'almost broke our benchmark' and that they initially thought it was a bug.
Source report
Claude Opus 5.5 has achieved a remarkable score of 2631 Elo on our writing benchmark, securing the #1 position by a significant margin.
Key Results
- First place: Claude Opus 5.5 — 2631 Elo
- Second place: Fable — 2324 Elo
- Gap: 307 points — the largest single jump recorded since we began tracking in June 2026
The model is also the first to clear 91 out of 100 on our rubrics.
Performance Notes
At maximum effort, Opus 5.5 requires:
- 17 minutes to write one script
- $3.43 per script
It is the slowest configuration on the entire board — by far. While not the most expensive, it ranks among the top five most costly.
More details on the effort and thinking levels of Opus 5.5 are available below.
Source
Whats_AINeutral / independent
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