To calculate a due date from a start date in Excel, add the required time period to the start date using a formula.
The right formula depends on whether your deadline is measured in calendar days, working days, or months.
Set up the start date and time period
Enter a valid Excel date in cell A2 and the number of days until the due date in B2.
For example, A2 might contain 10/15/2026, and B2 might contain 30.
Keep the date and day count in separate cells so you can update either value without editing the formula.
Excel stores dates as serial numbers, which lets you add days with ordinary arithmetic.
A cell that looks like a date is still a number formatted for display, so the result may need a date format applied.
Calculate a due date after a number of calendar days
Use this formula to add the number of calendar days in B2 to the start date in A2:
=A2+B2
If A2 is October 15, 2026, and B2 is 30, the result is November 14, 2026.
Calendar days include Saturdays, Sundays, and holidays.
If the due date is always a fixed period, you can enter the number directly.
For example, =A2+14 returns a date 14 calendar days after A2.
A cell reference is easier to maintain when the interval varies by task or record.
Calculate a due date after working days
For deadlines that count weekdays but skip weekends, use WORKDAY:
=WORKDAY(A2,B2)
With a start date of October 15, 2026, and 10 workdays in B2, the formula returns October 29, 2026.
The start date itself is not counted as one of the workdays; counting begins on the next working day.
To exclude holidays too, list the holiday dates in D2:D10 and use:
=WORKDAY(A2,B2,D2:D10)
Make sure the cells in D2:D10 contain real Excel dates.
Blank cells in the holiday range are ignored.
WORKDAY uses Saturday and Sunday as weekend days by default.
Use a custom weekend schedule
If your workweek has different weekend days, use WORKDAY.INTL.
Its second argument after the start date and day count controls the weekend pattern:
=WORKDAY.INTL(A2,B2,1,D2:D10)
The value 1 uses Saturday and Sunday as weekends, matching the default.
Other numeric codes and a seven-character weekend string can specify different schedules.
In the string, Monday is the first character and Sunday the seventh; use 1 for a nonworking day and 0 for a working day.
For example, 0000110 marks Friday and Saturday as weekends.
Calculate a due date after a number of months
For a deadline measured in whole months, use EDATE rather than adding a fixed number of days:
=EDATE(A2,B2)
If A2 is October 15, 2026, and B2 is 3, the result is January 15, 2027.
The function preserves the day of the month when possible.
If the target month is shorter, Excel returns its last day: =EDATE(DATE(2026,1,31),1) returns February 28, 2026.
To subtract months, enter a negative month count, such as =EDATE(A2,-1).
EDATE is useful for billing cycles, renewals, and other month-based schedules where a month should not be treated as 30 days.
Handle blank or invalid inputs
A simple addition formula may show a date even when the start-date cell is blank, because Excel treats a blank reference as zero.
To leave the result blank until both inputs are present, use:
=IF(OR(A2="",B2=""),"",A2+B2)
For a workday deadline with holidays, use:
=IF(OR(A2="",B2=""),"",WORKDAY(A2,B2,D2:D10))
These formulas do not validate every possible entry.
A text value where Excel expects a date or number can produce an error or an unintended result.
Use data validation to restrict the start-date column to dates and the interval column to whole numbers when other people will fill out the sheet.
Format and fill the due-date formula
If the result appears as a number such as 46310, the calculation may be correct but the cell is formatted as General or Number.
Select the result cell and apply a Date format from Excel’s Number Format menu.
Choose a format that makes the date unambiguous, such as 15-Oct-2026.
To calculate due dates for additional rows, enter the formula in C2 and fill it down.
The references will adjust by row, so the next formula will use A3 and B3.
If you store the data in an Excel Table, entering the formula in the due-date column generally fills it through the table automatically.
Formula compatibility
The basic addition formula works in modern desktop Excel, Excel for the web, and Google Sheets when the inputs are valid dates and numbers.
WORKDAY, WORKDAY.INTL, and EDATE are supported in current Excel versions and Google Sheets.
If an older Excel installation does not recognize one of these function names, check that version’s function support.
Excel settings can also affect how dates are entered and displayed.
For example, 10/11/2026 may be read as October 11 or November 10 depending on regional settings.
If a date is ambiguous, enter it using a clear format or build it with DATE(year,month,day), such as =DATE(2026,10,15)+30.
Choose the formula that matches the deadline rule
- Use
=A2+B2when every calendar day counts. - Use
=WORKDAY(A2,B2)when weekends should be skipped. - Use
=WORKDAY(A2,B2,D2:D10)when weekends and listed holidays should be skipped. - Use
=EDATE(A2,B2)when the interval is a number of months.
Confirm whether the start date counts as day one before choosing a formula.
The examples above add the interval after the start date; if your process counts the start date as the first day, adjust the day count to match that rule.