Check local times and compare cities at a glance.
View all →Plan by date and explore holidays and celebrations worldwide.
View all →Follow local time and traditions to discover each city’s rhythm.
View all articles →Find a week number and date range using ISO, Sunday-start or Monday-start rules.
Choose inputs and calculate to see your result.
Choose ISO weeks (Monday start, with at least four days in week 1) or a Sunday/Monday rule that places January 1 in week 1. Look up a date to find its week, or a week to find its dates.
Gregorian calendar, supported years 1900–2100. Historical local calendar reforms are not modeled.
Week-number rules vary by region. The interface language does not select a regional rule; choose the convention you need. Confirm official requirements for legal or administrative use.
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