ChronoUnitMONTHS

ChronoUnitMONTHS is a calendar-based time unit used to quantify the duration of calendar months. Because calendar months vary in length—from 28 to 31 days—ChronoUnitMONTHS measures time in whole months rather than a fixed number of days or hours. This unit is used in date-time calculations where the emphasis is on month-based increments rather than elapsed time in days.

In most implementations, ChronoUnitMONTHS represents completed calendar months between two temporal points. It is distinct from fixed-length units such as days or seconds, since adding or subtracting one ChronoUnitMONTHS to a date advances the date by one calendar month, preserving the concept of month boundaries and handling end-of-month scenarios according to the calendar rules in use. Edge cases can occur when the starting or resulting date falls on a day that does not exist in the target month (for example, the 31st), in which case libraries typically adjust to the closest valid date.

Common use cases include calculating eligibility windows, subscription cycles, billing periods, and age or service-duration calculations where the unit of interest is calendar months rather than absolute days. ChronoUnitMONTHS is often found in programming language libraries that model ISO-8601 time concepts and date arithmetic, facilitating clear and semantically meaningful month-based computations.

Related concepts include ChronoUnit in general, the MONTHS unit, Period for month-based intervals, and Duration for fixed-length time intervals. These tools are used together to perform robust date-time calculations across calendars.