Add or Subtract Days
What date is 90 days from today? Add or subtract any amount of time from any date.
How month and year arithmetic works
Adding days or weeks is exact. Adding months or years moves the calendar month and keeps the day-of-month, clamping when it doesn't exist: January 31 + 1 month gives February 28 (or 29 in a leap year). This is the convention used by contracts, spreadsheets and most law.
Common uses
Probation and notice periods (90 days from a start date), invoice due dates (net 30), visa windows (180 days), medication courses, and project deadlines. For the gap between two known dates use the days between dates calculator instead.