Date math
Add and subtract dates, count business days, and measure the span between two moments.
Tue 1970-03-31 17:00 is 3 months after Wed 1969-12-31 09:00.
45 business days after Wed 1969-12-31 09:00 is Wed 1970-03-04 09:00, stepping over 18 non-working days.
read as 45 business days after now, skipping weekends — Wed 1970-03-04 18:00
A business-day offset typed here skips weekends only. The step section above also skips the holiday list.
Business days count the half-open span: the start date counts, the end date does not, so Monday to Friday is four. Month steps clamp rather than overflow — 31 January plus one month is the last day of February, never the third of March. Calendar units move calendar fields, so a day stays the same wall-clock time across a change of clocks.
Date arithmetic is full of small traps: months are different lengths, leap years exist, and business-day counting has to skip weekends. Doing it in your head is how off-by-one deadlines happen.
Add or subtract any unit from a date, or take the difference between two dates in days, weeks, months and years at once. The business-day mode counts only weekdays, which is the one people actually need for delivery dates and SLAs.
What people open it for
- Working out a deadline a set number of working days out
- Measuring how long something has been open
- Adding a retention period to a date correctly
In the terminal
tools datemath
Every utility is also a command in the desktop's shell.