Activity Duration Types Explained with Example

1. Duration Types in Primavera P6
Duration Type is a setting which allows the user to control how the duration, resource units, and resource units/time are synchronized for activities, so that
the following equation is always true:
Original, Remaining or Planned Duration = (Budgeted, Remaining or Planned Units) / (Budgeted, Remaining or Planned Units/Time)
If the activity is not started, the names of the values are
: Original Duration x Budgeted Units/Time = Budgeted Units
If the activity has started, the names of the values are
: Remaining Duration x Remaining Units/Time = Remaining Units
The following table lists the value that changes to balance the equation
Duration x Units/Time = Units
The following table illustrates how the variables in the above equation changes when you change one among them in each of the Activity duration types.
Duration Type
Fixed Units/Time
Fixed Duration
and Units/Time
Fixed Units
Fixed Duration
and Units
When You Change
Duration, what
changes?
Units
Units
When you change
units/time,
what changes?
Duration
Units
When you change
units, what
changes?
Duration
Units/Time
When you add a
resource, what
changes?
Duration
Units
Units/Time
Units/Time
Duration
Units
Duration
Units/Time
Duration
Units/Time
Table 1. Activity duration types

2. The duration type is set at the Project Details level for the Project, but can be modified per activity. Your organization’s project
needs will help to determine which duration type to use. We’ll be discussing in the following section as of what situation forces you to
choose a particular Duration type.
As a hint, if you are adding resources to activities and you do NOT want P6 to recalculate the existing resources units, duration and
units/time, go to Edit, User Preferences from the Menu bar, select the Calculations tab and select the Preserve the Units, Duration and
Units/Time for existing assignments radio button.
Example:Now let us consider a Case and work on it to get a better understanding on the Activity duration types.
Given Case :Consider a software company where a resource is assigned design work of a particular website. It is estimated that the design
work would be completed within 5 working days of the resource. The particular resource has a regular shift duration of 8 hours /day.
Find what happens to values of the Original duration, budgeted units/time and Budgeted units when
i.
Original duration changes to 10 days
ii.
Budgeted units/time changes to 10hours/day
iii.
Budgeted units of work changes to 20 hours
In each of the activity duration types.

3. Findings:
Original Duration =5 days ,
Budgeted units/time = 8h/d
From the formula we know Budgeted units = Original Duration X Budgeted units/time = 8 x 5 = 40 hours
Type I :-Fixed Units / Time
Units/time for the resources remains fixed; Even when activity duration or budgeted units changes. Used when resources with
productivity output per time period is fixed. Mostly used when Activity type is Resource Dependent. This option is selected if your
organization is concerned with leveling resources and you assign resources specific hours per day on activities.
Original Duration = Budgeted Units / Budgeted Units/Time
Duration Type
When You Change Duration,
When you change units/time,
When you change units, what
what
what changes?
changes?
Duration
Duration
changes?
Fixed Units/Time
Units
Table 1.1.1 Fixes Units / Time

4. Coming back to our case
Where Original Duration =5 days ; Budgeted units/time = 8h/d And Budgeted units = 40 hours.
i.e. Original Duration = units / (units/time)  5= 40 / 8
We were asked to analyze what would happen if
Changes made
(i) Original Duration Changes
duration
(Units )/
(Units/time)
from 40 to 20
Budgeted
Original
Budgeted
Original
Budgeted
units
units/time
Duration
units
Duration
units/time
80h
=>
from 8 to 10
Budgeted
Original
(iii) Units changes
from 5 to 10 days
Values changed
(ii) Units / time changes
8h/d
4d
40h
2.5d
8h/d
10=> 80/8
4 => 40/10
Table 1.1.2 Fixes Units / Time Workout
2.5 => 20/8

5. Type II: Fixed Duration & Units/Time
Activity duration and units / time remains fixed; even if remaining unit’s changes. Mostly used when Activity type is Task Dependent
Activity. Organizations which have the project deadline fixed and is also concerned with leveling resources used this activity duration type.
Organization may consider increasing number of resources to keep the resources leveled. Since this activity is Task dependant and activity
duration type is fixed duration & Units/time there would be no layoff in duration time.
Original Duration = Budgeted Units / Budgeted Units/Time
Duration Type
When You Change Duration,
When you change units/time,
When you change units, what
what
what changes?
changes?
Units
Units/Time
changes?
Fixed Duration and
Units
Units/Time
Table 1.2.1 Fixed Duration & Units/Time

6. Given Original Duration =5 days ; Budgeted units/time = 8h/d And Budgeted units = 40 hours.
Changes made
(i) Original Duration Changes
duration
(Units )/
(Units/time)
from 40 to 20
Budgeted
Original
Budgeted
Original
Budgeted
units
units/time
Duration
units
Duration
units/time
80h
=>
8 to 10
Budgeted
Original
(iii) Units changes
from 5 to 10 days
Values changed
(ii) Units / time changes from
8h/d
5d
50h
5d
4h/d
10=> 80/8
5 => 50/10
Table 1.2.2 Fixed Duration & Units/Time Workout
5 => 20/4*

7. Type III :-Fixed Units
This duration type is chosen if you want the activity units to be fixed even when duration or resource units per time changes. Total
amount of Work is fixed. Used when Activity type is Resource Dependent Activities. Unlike previous Duration types increasing resources
decreases the activity duration. Generally used when you have resource under contract basis and you have X units of work to get to be done
from that particular resource.
Original Duration = Budgeted Units / Budgeted Units/Time
Duration Type
When You Change Duration,
When you change units/time,
When you change units, what
what
what changes?
changes?
Duration
Duration
changes?
Fixed Units
Units/Time
Table 1.3.1 Fixed Units

8. Given Original Duration =5 days ; Budgeted units/time = 8h/d And Budgeted units = 40 hours.
Changes made
(i) Original Duration Changes
duration
(Units )/
(Units/time)
from 40 to 20
Budgeted
Original
Budgeted
Original
Budgeted
units
units/time
Duration
units
Duration
units/time
40h
=>
8 to 10
Budgeted
Original
(iii) Units changes
from 5 to 10 days
Values changed
(ii) Units / time changes from
4h/d
4d
40h
2.5d
8h/d
10=> 40/4
4 => 40/4
2.5 => 20/8
Table 1.3.2 Fixed Units Workout
Type IV :-Fixed Duration & Units
Activity duration and Units to remain constant even when the units/time changes. Mostly used when time period and the total
amount of work are fixed. Used when Activity type is Task Dependent Activities. Rate at which a resource can work on the activity can be
changed. You could use this if your organization is more concerned about coming in on the schedule date and within the costs (which are
usually associated with the units)
Original Duration = Budgeted Units / Budgeted Units/Time

9. Duration Type
When You Change Duration,
When you change units/time,
When you change units, what
what
what changes?
changes?
Units
Units/Time
changes?
Fixed Duration and Units
Units/Time
Table 1.4.1 Fixed Duration & Units
Given Original Duration =5 days ; Budgeted units/time = 8h/d And Budgeted units = 40 hours.
Changes made
(i) Original Duration Changes
duration
(Units )/
(Units/time)
from 40 to 20
Budgeted
Original
Budgeted
Original
Budgeted
units
units/time
Duration
units
Duration
units/time
40h
=>
8 to 10
Budgeted
Original
(iii) Units changes
from 5 to 10 days
Values changed
(ii) Units / time changes from
4h/d
5
50
5d
4h/d
10=> 40/4
5 => 50/5*
Table 1.4.2 Fixed Duration & Units Workout
5 => 20/4

10. Summary
Given Original Duration 5days; Budgeted Units 40hours; Budgeted Units/ time 8hours/day. The following table summarizes as of what
happens to the variables in each of the activity duration types.
Units / time changes from 8 to 10
Units changes from 40 to 20
Budgeted units
Budgeted
Original Duration
Budgeted units
Original Duration
Budgeted
(Or. Val:- 40h)
Type
Duration
Original Duration Changes from 5 to 10
units/time(Or. Val:-
(Or. Val:- 5d)
(Or. Val:- 40h)
(Or. Val:- 5d)
units/time
8h/d)
Fixed Units / Time
(Or. Val:- 8h/d)
80h
8h/d
4d
40h
2.5d
8h/d
80h
8h/d
5d
50h
5d
4h/d*
Fixed Units
40h
4h/d
4d
40h
2.5d
8h/d
Fixed Duration & Units
40h
4h/d
5d
50h*
5d
4h/d
Fixed Duration &
Units/Time
Table 2: Activity duration table chart
Or.Val - Original Value
* - in certain cases original duration remains fixed and the other fixed variable is forced to changed.
Reference:https://ccsspl123-public.sharepoint.com/Support%20Documents/duration%20types-Activity.pdf
http://www.projectcontrolsonline.com/Forum/tabid/65/forumid/13/threadid/529/scope/posts/Default.aspx