Use calendar days vs. working days?

When I add a prerequisite with delays, the delay is in working days (according to the resource calendar).
How can I make a prerequisite where the delay is a fixed number of calendar days?


  • task 1: 11/2/2015 (Monday)
  • task 2: task 1 + 10d = 11/17 (10 working days)

Wanted (in certain situations):

  • task 2: task 1 + 10d = 11/13 (10 calendar days)

I want to avoid the workaround: assigning the task to a resource that uses a 7days-a-week schedule.

Attached a screenshot of what I mean. I have created section 1, copied it to section 2 and 3 and changed the start date.
Section 1: starting on Monday. Both finish Friday.
Section 2: starting on Tuesday. 5 working days finishes Mon Nov 9, 5 calendar days finishes Sat Nov 7.
Section 2: starting on Thursday. 5 working days finishes Wed Nov 11, 5 calendar days finishes Mon Nov 9.

I achieve this by assigning it to a “calendar days” resource, which uses a 7 days-a-week schedule. And by using the default setting of “adjust task duration” when changing resource assignments.
Still confusing: the duration is shown as 4d or 3d, which is the working days of the default schedule. Effort for both is 1w, based on the schedule of that resource.

I am hoping there is an easier and clearer way of achieving this.
Additional request: show the weekends in the GANTT view (grayed out).

An example: paint drying takes 1.5 days, and is not related to working hours.
For MS Project I could use edays.
Similar to the request that was made in 2008.

In another thread, a similar issue with dependencies that elapse in calendar time was resolved by changing the project schedule to 24/7 and then setting up resource schedules as appropriate. I think the same could work here, unless you find it causes whatever problem you were facing assigning the task to a 24/7 resource…

Hi lizard, the workaround you mention is the one I described in my original post. ;-)
My question/request: is there an easier way?
The workaround means the reader needs to know they should ignore the duration field (I now do this by giving the row a different color), and it also means that the GANTT does not show the real end date (if it is a non-working day/time).

And if want to offset a task (e.g. task 2 starts 20 elapsed days after task 1), then I am forced to add that offset as a task. Some prefer it that way because it makes it more explicit what the offset is based on, but now I am forced to use it.

You suggest using a 24x7 default calendar. I am hesitant doing that, as elapsed is the exception and not the default. It would mean I create custom calendar(s) for all regular resources, and often I have tasks that are not assigned to someone which means I would need to create a “TBD” resource that has a 8x5 calendar.

In MS project I simply used edays (elapsed days) instead of days (working days). Either for task durations/efforts, or for constraint offsets.

@lizard: suggestions about:

  • using edays instead of the workaround?
  • showing weekends in the GANTT view?

OmniPlan does not directly support elapsed days.

To show weekends in the Gantt view, choose an option from the Non-Working Time submenu of the View menu.

If you use the 24x7 calendar for the project…

  • You can set an elapsed dependency offset by editing the dependency (on either of the tasks involved). If you want a work day dependency offset, then you would have to create a “task” for it.

  • You can create a resource group and set the normal workday calendar on that group. Then move all your other resources and groups inside that group so they inherit it.

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Thanks lizard.
Great to see the weekends (and other non-working time) can now be selected in v3.
For the edays: any plans to implement this? The workaround works, but is not ideal (nor is is compatible when im-/exporting from MS Project)

We have had a couple requests for elapsed time calculations, and I will add your comments to the feature request. I cannot speak to future plans.