Across January to May 2026, Epoch AI's capabilities index puts the best open-weight models behind the frontier closed models by an average of four months
Epoch AI measured the average time it takes for the best open-weight models to achieve the same performance as state-of-the-art closed models. This was calculated daily from January 1, 2026, through May 28, 2026, using their Epoch Capabilities Index (ECI). The ECI is a composite measure of model capability across various benchmarks.
Verified 2026-08-04
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Freely downloadable models trail the best closed ones only briefly, which limits how long a lead lasts.
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