# Calculating duration by calendar days in ms project

• ### Question

• Hi,

I could use a help with counting the finish date based on a start date and duration that is entered in months.

I want Project to count whole month and not only working days of a month. When I entered 12 months, the finish date was earlier than that day next year. I just want it simply to calculate calendar days.

Do you know where to change working days to calendar days in MS Project ?

Project -> Change Working Time -> Work week -> Details      was not helpful :(

Best regards,

Sanja

Wednesday, August 16, 2017 10:11 AM

• Sanja,

Re. your caption: "Calculating duration by calendar days in ms project."  It's very easy to calculate duration by calendar days - just use "edays" (elapsed days) in your duration.  There are lots of complications that go along with that, however, so study up.

Re. your actual question: don't use "months" for durations if you want to manipulate dates.  Unlike hour, day, and week - "month" is not a practical unit of time/duration for computer-based calculation.  Project (Options|Schedule) allows you to specify "Days per month" for a project (20 is the default, based on a 5-day week and a 4-week standard "month").  This is simply a factor for converting your entry of "months" into work-minutes - the number that gets stored.  If you enter durations in "emonths" (elapsed months) instead, Project will make the conversion assuming 30.0 elapsed days per month - this is not selectable.  None of these will meet your requirement for convenient date-manipulation.

Wednesday, August 16, 2017 12:09 PM

### All replies

• Sanja,

Re. your caption: "Calculating duration by calendar days in ms project."  It's very easy to calculate duration by calendar days - just use "edays" (elapsed days) in your duration.  There are lots of complications that go along with that, however, so study up.

Re. your actual question: don't use "months" for durations if you want to manipulate dates.  Unlike hour, day, and week - "month" is not a practical unit of time/duration for computer-based calculation.  Project (Options|Schedule) allows you to specify "Days per month" for a project (20 is the default, based on a 5-day week and a 4-week standard "month").  This is simply a factor for converting your entry of "months" into work-minutes - the number that gets stored.  If you enter durations in "emonths" (elapsed months) instead, Project will make the conversion assuming 30.0 elapsed days per month - this is not selectable.  None of these will meet your requirement for convenient date-manipulation.

Wednesday, August 16, 2017 12:09 PM
• Thank you, Tom.

Duration in months is used for high-level PM plan, so I find this info pretty much helpful.

"emons" is the hint I was looking for!

Sanja

Wednesday, August 16, 2017 1:22 PM
• There are two ways of doing it.

You need to use the 24 Hours calendar and a formula

ProjDateDiff(date1,date2,Calendar)

Use a Text field column, then customize it by a formula by right clicking it and use Custom Fields, then Select Formula and use this:

For Hours

Format(ProjDateDiff([Start],[Finish],"24 Hours")/60,"0.00") & " h"

For Days

Format(ProjDateDiff([Start],[Finish],"24 Hours")/1440,"0.00") & " d"

For Weeks

Format(ProjDateDiff([Start],[Finish],"24 Hours")/10080,"0.00") & " w"

This will display the calendar duration as calendar time not duration related to work or calendars in MS Project.

Tuesday, July 17, 2018 6:39 PM