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Timeline Model release SIU-LDG-2025-019 SI Index +1.50

Claude Opus 4.5 is measured at a task horizon of nearly five hours

METR estimates the 50% time horizon of Anthropic's new flagship at 4 hours 53 minutes, the first point estimate past half a workday.

Log-scale chart of METR time horizons through November 2025, with Claude Opus 4.5 highlighted near five hours
METR 50% time horizons by release date, through Claude Opus 4.5. Chart: SI USA, from METR data

The measurement comes from METR’s Time Horizon 1.1 suite, which it published with results for models going back to 2019. The interval is wide; the Index uses the point estimate, as it does for every horizon move.

Index treatment. Autonomous task horizon of one workday moves to 0.5.