The calendar is a game mechanic in The Sims 4 that allows players to set dates for planned social events. The calendar also showcases the work and school schedules of household Sims, birthdays, moon phases, festivals, seasons, holidays and weather. Social events cannot be planned more than two weeks in advance in the calendar.
The calendar was originally a feature exclusive to The Sims 4: Seasons, but was later introduced into the base game in patch 115, with the release of The Sims 4: Cottage Living. Some improvements have been added to it, such as the ability to favorite and sort events, festivals and holidays.
The duration of a season can be set to 1, 2 or 4 weeks. The default length is 1 week.[1] The first day of the week will always be Sunday.