NINEHOUND / CALENDAR & CULTURE TOOLS
January 1 can belong to the previous ISO week-year. Check both labels.
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WORKED EXAMPLE
Gregorian date：2021-01-01
2020-12-28 → 2021-01-03 · Monday–Sunday
Weeks begin on Monday. Week 1 contains January 4; the ISO week-year can differ from the Gregorian year.
The answer includes Monday and Sunday boundaries. January 1, 2021 belongs to week 53 of 2020 under this convention.
Explore the calendar here. Find NineHound’s founder, Lao Heshan Daoren / Sun Xingzhe, and the wider I Ching and life-chart project.
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