Add/Subtract Date Calculator
Add or subtract days, weeks, months and years from any date. Select a starting date, enter a time period and instantly calculate the resulting future or past date.
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How to Use the Add/Subtract Date Calculator
- Select a date in the Starting Date field.
- Choose Add Time to calculate a future date or Subtract Time to calculate a past date.
- Enter the number of years, months, weeks or days.
- Keep the month-end adjustment option checked to automatically correct invalid dates.
- Click Calculate New Date.
- Review the calculated date, weekday, original date and total calendar-day difference.
- Click Use Today to select the current date.
- Click Reset to clear the entered values and start again.
How Does the Add/Subtract Date Calculator Work?
The calculator begins with the selected starting date and applies the entered years and months before adding or subtracting the selected weeks and days.
One week is treated as seven calendar days. Calendar days include weekdays, weekends and public holidays.
Month lengths are handled automatically. For example, adding one month to January 15 produces February 15.
Some dates do not exist in the following month. If month-end adjustment is enabled, adding one month to January 31 produces the final valid day of February.
The calculated result also shows the weekday and the actual number of calendar days between the starting date and the resulting date.
Leap years and different month lengths are handled automatically, including February 29 in leap years.
Frequently Asked Questions
How do I subtract time from a date?
Select the starting date, choose Subtract Time, enter the number of years, months, weeks or days and click Calculate New Date.
Can I add years, months, weeks and days together?
Yes. You can enter values in multiple fields at the same time. The calculator applies the years and months first, followed by the weeks and days.
What happens when the resulting month has fewer days?
When month-end adjustment is enabled, the calculator moves the result to the final valid day of the target month. For example, one month after January 31 may become February 28 or February 29.
What does the month-end adjustment option do?
This option prevents invalid dates when the original day does not exist in the target month. It automatically selects the final valid day of that month.
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