monthsand

Monthsand is a calendar concept used in speculative fiction and analyses of timekeeping. In its standard form, the year consists of twelve 30-day months, for 360 days. A five-day intercalary period at the end of the year completes the 365-day solar year, and every fourth year adds a sixth intercalary day to reach 366 days in leap years.

The name combines 'month' and 'sand,' reflecting desert imagery common in the settings where monthsand is proposed; some writers note it also evokes the passage of time as grains of sand in an hourglass.

Monthsand is used in world-building to illustrate how societies might organize time, commerce, and seasonal life. While the core structure is fixed, authors variably place the intercalary days, assign month names, and decide whether the week remains seven days or is redefined.

Variations exist across fictional cultures; some align months with lunar cycles, producing months of 29 or 30 days with irregular intercalaries; others keep purely solar months.

See also: calendar, timekeeping, lunar calendars, worldbuilding.