METR revises the horizon doubling to 89 days
After expanding its suite from 170 to 228 tasks, METR re-estimated the trend: the time-horizon doubling since 2024 is 89 days rather than 109, and since 2023 it is 131 days rather than 165.
Why it matters
The most cited number about the pace of AI - a seven-month doubling - was restated by its own authors as under three months for recent years, and the change came from fixing the instrument rather than from new models.
The suite grew from 170 to 228 tasks: 73 added, 15 removed, 53 updated. Long tasks, those estimated to take a human eight hours or more, grew from 14 to 31. Under the new suite the post-2023 doubling time is 131 days against 165 under the previous one, and since 2024 it is 89 days against 109, roughly 20 per cent faster in both windows. The hybrid trend over 2019-2025 is unchanged at 196 days, about seven months. Confidence intervals tightened: Claude Opus 4.5 is estimated at 320 minutes with an interval of 170 to 729, against 289 with an interval of 110 to 1268 before. METR notes that the trend is sensitive to task composition.