How the date is moved
Days and weeks add a fixed number of midnights. Months and years keep the day of the month when they can. If you add one month to January 31, many calendars land on February 28 (or 29 in a leap year). This page follows that common rule.
Use it for “what day is 90 days from today,” return windows, and notice periods. It does not skip holidays.
Common questions
Does 1 month always mean 30 days?
No. One month follows the calendar. 30 days is always 30 midnights. Pick the unit you mean.
What about time zones?
This page uses your computer’s local calendar date only.