bwday

Bwday, short for business day, is a term used in software to perform date calculations that respect a working-day calendar. In many programming and data-analysis libraries, bwday denotes either a function that checks whether a given date is a business day or a set of operations that advances or retreats dates by a specified number of business days. The central aim is to treat weekends and listed holidays as non-working days when performing date arithmetic.

Typical features include: testing a date for business-day status within a given calendar; adding or subtracting n business days from a date; counting the number of business days between two dates; and returning either the resulting date or the position of a date within a sequence of business days. Support for multiple calendars is common, allowing different regions or organizations to define workweeks and holidays. Users can often supply a custom holiday list or rely on built-in calendars.

Bwday calculations are common in finance, logistics, and scheduling, where settlement, delivery, or production times must reflect actual working days rather than calendar days. They are also used in time-series analysis to align events to business-day indexes. The exact syntax, default weekends, and holiday-handling rules vary by language and library, so developers consult the respective documentation.

See also: business day, calendar, holiday, date arithmetic.