# Calculating the Start Month of a task relative to the start date of the project (Project Month Number)

• ### Question

• Hi,

I need to report a project in term of Months since the start of the project.

to do so I created a custom field (Text 1), with thsi formula: (ProjDateDiff([Project Start];[Start];[Project Calendar])/[Minutes Per Day])

As pero this blog: https://www.mpug.com/articles/project-date-numbering/

However, I need the relative month numer.

My naive approach was dividing by 30 for an estimate. But the errors start to become significant halfway through the second year of the project ((ProjDateDiff([Project Start];[Start];[Project Calendar])/[Minutes Per Day])/30).

Any ideas would be welcomed,

Thank you,

Sunday, August 25, 2019 11:39 AM

• Mata,

I assume you want calendar months, not working months. Try the following formula

Text1 = "Mon " & DateDiff("m",[Project Start],[Start]) + 1

Hope this helps.

John

• Edited by Sunday, August 25, 2019 3:35 PM oops
• Marked as answer by Monday, August 26, 2019 8:12 AM
Sunday, August 25, 2019 3:33 PM

### All replies

• Mata,

I assume you want calendar months, not working months. Try the following formula

Text1 = "Mon " & DateDiff("m",[Project Start],[Start]) + 1

Hope this helps.

John

• Edited by Sunday, August 25, 2019 3:35 PM oops
• Marked as answer by Monday, August 26, 2019 8:12 AM
Sunday, August 25, 2019 3:33 PM
• Thank you!
Monday, August 26, 2019 8:12 AM
• Mata,

You're welcome and thanks for the feedback.

John

Monday, August 26, 2019 7:31 PM