Loona Calculators
Businesses, schools and logistics run on week numbers, but calendars rarely print them. Pick any date and instantly get its ISO week number, its day of the year, the days remaining, and its calendar quarter.
Weeks start on Monday, and week 1 is the week containing the year's first Thursday. It is the standard used across Europe, in business planning and in most software.
Because an ISO week belongs to the year holding its Thursday. 1 January 2023, for instance, is in week 52 of ISO year 2022 — the calculator shows both the week and its ISO year.
Delivery promises ('ships in week 44'), school terms, project plans and production schedules are all commonly quoted in ISO weeks.