# How to calculate a Date plus or minus a certain number of days

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Did you mean:  5 - Automation Enthusiast

Hi all,
I’m sure I’m just missing something easy but here is my problem. I have an employee start date field and a field with numbers of days. I have tasks that need to be done 5 days before the employee starts, 1 day before the employee starts, and so on and so forth. So I want to calculate a field using the Start Day and Number of Days to calculate the Due Date of the task based upon number of days.

So if my start date is 6/20/19 and my Number of days field is -5, I want a formula to return 6/15/19. I have tried the formula below but I get NaN returned. Thanks for any guidance and help!

DATETIME_FORMAT({Start Date},‘MM/DD/YY’)+{Number of days}

1 Solution

Accepted Solutions  18 - Pluto

Date calculations are done using the DATEADD function. In your case, the formula would be:

``````DATETIME_FORMAT(DATEADD({Start Date}, {Number of days}, 'days'), 'MM/DD/YY')
``````

Full function reference is here:

2 Replies 2  18 - Pluto

Date calculations are done using the DATEADD function. In your case, the formula would be:

``````DATETIME_FORMAT(DATEADD({Start Date}, {Number of days}, 'days'), 'MM/DD/YY')
``````

Full function reference is here:  5 - Automation Enthusiast

Thank you so much! That worked! 