OpenAI's GPT-6 Astra tops the Epoch Capabilities Index (ECI) with a score of 166, ahead of Claude Fable 5.1 at 164 and GPT-5.6 Sol at 162. Its Math-ECI of 170 sets a new record, but on software engineering benchmarks its SWE-ECI of 164 still lags behind Fable 5.1's 167.

We tested Pangram, GPTZero, and Originality.ai on human and AI text. All three caught nearly every passage written from a simple prompt, but missed roughly one in five passages imitating a specific author's style.

The share of working days on which OpenAI's Codex collaborators merged very-high-effort code rose from about 2% in Q2 2025 to about 8% in Q2 2026.

GPT-4 topped Epoch's Capabilities Index (ECI) for roughly a year after its March 2023 release — no model since has led for as long. The second-longest reign, by o1, lasted barely three months.

Household income of weekly AI users ranges from 80% earning $100K+ for Claude to 37% for Meta AI in the Epoch AI/Ipsos survey.

Claude was the only AI tool to show significant usage growth across three Epoch AI/Ipsos survey waves in March-April 2026.

The best score on the Epoch Capabilities Index grew almost twice as fast over the last two years as it did over the two years before that, with a 90% acceleration in April 2024.

Epoch’s Capabilities Index stitches together benchmarks across a wide range of difficulties. We show how scores can be interpreted by mapping them back to expected benchmark performance.