Change Hours/Day in Calendar but keep Activity Duration unchanged in Primavera P6

We make a schedule using 8 hours/day calendar.


Now we want to change to 10 hours/day calendar.


We can see the Activity Duration now change to 8 days and Project Completion date is now earlier.

How can we change Hours/day but keep duration unchanged?

I will show you how to do it.

Go to Tool -> Global change. Click New.


Enter Data as below picture:


Click on Change button. Primavera will show us a Preview. Then click on Commit Change


Now we can see Activity Duration change back to 10 days and Project completion date is the same with original one.




15 thoughts on “Change Hours/Day in Calendar but keep Activity Duration unchanged in Primavera P6

Add yours

  1. Thanks, It’s great.
    But if we change calendar form 6 days to 7 days. The project finish will change also. Is there any way to keep project finish as it is?


    1. Changing from 6 days to 7 days, I think we don’t know what is the ratio between new value and old value. It’s not a constant number.
      Only when changing hour, we know the ratio. For example, from 8 hours to 10 hours, the ratio is always 1.25


      1. I think in this before but I thought you might have something. You are right there is no ratio for this.
        Thanks again.


  2. Store in UserDefined field. Divide /6 the O.D.. Then to bring back to original values Multiply the UserDefinedfield x7.. You have to use the Global change twice, because 6/7 is irrational number. Important thing here is you just have first to store the O.D. in UserDefined Field, then when you change to any calendar you have to multiply it based on the hrs/da of that calendar.


  3. Same aduration for each activity, the non-working day is not counted which P6 will just skip it. Number of working days remain the same. The Project Calendar Days wills become longer, but the individual activity working number of days remain the same.


  4. Dear sir,

    I wish your help on my three doubts in the calender

    if i change calender’s of resources in already assigned calendar whether it will reflect in the activity?
    2.i have to use three calender , 7 days /8hr . 6 day/8hr, 6 day /10hr, 5 day / 8hr calender . When i am using it my float showing decimal. how i can avoid it.
    as explaned i have to use three calender in project. but for all the activity i have to use common resources cash flow . which calender i have to use. Wishing your suggestion.

    Thank you


Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a website or blog at

Up ↑