GWN Tools · Date & Time

Date Calculator

Add or subtract days, weeks, months, or years from any start date to find the resulting date — including the day of the week it lands on.

resulting date
Day of week
Shift applied

Month and year shifts roll forward when a day does not exist (e.g. Jan 31 + 1 month). Dates use local time.

About the date calculator

What does this calculator do? It adds or subtracts a number of days, weeks, months, or years from a start date and returns the resulting date along with its day of the week.

How do you add or subtract time from a date?

Pick a start date, choose whether to add or subtract, enter an amount, and choose a unit of days, weeks, months, or years. The calculator shifts the start date by that amount using calendar math and returns the resulting date.

What happens when adding a month lands on a day that does not exist?

When a month-based shift would land on a day that the target month does not have, such as January 31 plus one month, the result rolls into the next month so it stays a valid calendar date. Year-based shifts behave the same way for February 29.

Does the result show the day of the week?

Yes. The resulting date is shown with its full weekday name, such as Monday or Friday, so you can see at a glance which day of the week it falls on.