Date Add/Subtract Calculator

Add or subtract days, weeks, months, or years from a reference date.

When to use?

Use it to add or subtract a period from a reference date — like 3 months after a contract date, or 14 days after an order date.

Enter a whole number from 0 to 10,000. Choose the unit from days, weeks, months, or years.

Days and weeks add by calendar date; month/year calculations apply end-of-month correction, snapping nonexistent dates to that month's last day.

Calculate a due date - Find a date N days or N months after a reference date.
Check a contract expiry - Add the contract term to the start date to find the expiry.
Back-calculate a past date - Subtract a period from a reference date to find a past date.

Handling of leap days and month-end dates (e.g. subtracting a month from the 31st) can vary by convention.
Time-zone settings can cause a one-day difference in some cases.

Yes. Adding 1 month to January 31 snaps to the last day of February.

Enter a negative value to calculate a date before the reference date.

Yes. Entering weeks calculates in 7-day steps to show the result date.

Yes. It calculates by the calendar, so Feb 29 in leap years is reflected accurately.

Date Difference Calculator - Calculate the number of days between two dates, or the date N days from a reference date.
D-Day Calculator - Show the days remaining until, or elapsed since, a target date based on today.
Business Day Calculator - Calculate a date N business days out or the number of business days, excluding weekends.
Date Range Generator - Generate a list of all dates between a start and end date at once.
Age Calculator - Calculate your exact age, this year's birthday status, and days until your next birthday.
Time Calculator - Add or subtract time from a clock time, and calculate the interval between two times.