Skip to content

Epoch Capabilities Index (ECI)

The Epoch Capabilities Index is Epoch AI's composite score of model capability, estimated from results across many benchmarks with a statistical model so that models can be placed on one scale.

Because it combines many benchmarks, ECI is less sensitive to any single test. It comes with a confidence interval, shown on each model page. New models receive a score only after Epoch AI has evaluated them.

Related ranking: LLM leaderboard

  1. 1.GPT-6 Astra OpenAI166.6
  2. 2.Claude Fable 5.1 Anthropic165.0
  3. 3.Claude Fable 5 Anthropic163.6
  4. 4.Claude Opus 5 Anthropic162.7
  5. 5.GPT-5.5 Pro OpenAI162.4

Ranked by the Epoch Capabilities Index (ECI) - Epoch AI's statistical model over dozens of benchmarks. Source: Epoch AI. Full ranking

Related terms

Explanation written by AI Stats Live editors; last reviewed 29 Sep 2026. Examples and rankings update automatically from the sources listed on the methodology page.