Find ISO week dates or explicitly selected Sunday / January 1 week numbers, including year boundaries.
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All inputs stay in this page. No uploads or application history. Input edits invalidate generated outputs. Numeric quick sliders never clamp wider exact fields. ISO week 1 contains January 4 / the first Thursday; its year can differ from the calendar year. Sunday / January 1 numbering is an explicitly separate convention and resets at each January 1. Supported dates 0001–9999; week boundaries outside that domain are labeled. Calculation worker deadline: 10 seconds.
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ISO week 1 contains January 4 / the first Thursday; its year can differ from the calendar year. Sunday / January 1 numbering is an explicitly separate convention and resets at each January 1. Supported dates 0001–9999; week boundaries outside that domain are labeled.
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No. Weekend/holiday rules are supplied by you; no regional legal calendar is inferred. Time-zone calculations use the browser’s installed rules. The Meeting planner rejects skipped local times and requires an explicit occurrence for repeated times.
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