Anthropic ECI - September 2026 Fit (Opus 5.5 System Card): leaderboard
Metric: AECI Score. Source: www-cdn.anthropic.com. Saturation forecast: Around August 2028. 5 models tracked.
Top models
| # | Model | Score |
|---|---|---|
| 1 | Claude Opus 5.5 (Max) | 169.36 |
| 2 | Claude Opus 5 (Max) | 165.18 |
| 3 | Claude Mythos 5 | 164.49 |
| 4 | Claude Mythos Preview | 161.88 |
Interactive version: theaggregate.ai/benchmark?slug=anthropic-eci-september-2026-fit-opus-5-5-system-card · How It Works · Data refreshed daily, snapshot 2026-09-24.