I am struggling with Work/Duration/Units.

Example: I have a product that takes 184 hrs to build, we typically have 5-6 guys working on it and in real time, takes about a week to complete. When I enter the task in project and assign the resources, it appears that it will take a month to build? But I know that's not the case.

What am I doing wrong?

  • How many hours per day do people work? Are they allocated to this job 100% or do they do other things? Is it more important to you to reflect 184 hours or that it takes a week elapsed?
    – Marv Mills
    May 16, 2016 at 11:01
  • We have 2 shifts, and they work on 2-3 projects at the same time. I need to reflect the 184 hours. I thought as I assign additional resources, welders in this case, that it would shorten the time elapsed but still reflect 184 total hours to complete.
    – user23439
    May 16, 2016 at 13:20
  • 1
    it may help to understand that "Fixed Work/Units/Duration" are there for you to tell MS Project how to adjust values when you change something in your schedule. Use them/change them as needed to have the tool adjust based on your inputs. I know this doesn't explain them, but I think you may be assuming a great deal of how the tool should work vs how it does. Create a simple (3 task) schedule and get comfortable with these setting and the changes you make. This is (imho) critical to learning MS Project.
    – Al Biglan
    May 17, 2016 at 1:59
  • Try using the task usage view for a single task. You can assign hours at the resource level by task and see how they're working through time.
    – Hey Romey
    May 18, 2016 at 0:27
  • If you want the 184 hours of work split between the resources, you need to make sure the task is Effort Driven and not Fixed Duration. Earlier versions of Project - Effort Driven was the default. In Project 2013 and later it is no longer effort driven.
    – JulieS
    Jun 2, 2016 at 22:08

2 Answers 2


Firstly you should understand the difference between "effort" & "duration". You can read this article - http://www.pmbypm.com/difference-project-effort-and-duration/

Let's talk about 3 different terms

  1. Work - In MS Project, "effort" & "work" are synonymous. It is the a/m of labor units to complete a task.
  2. Duration - It is the length of time to complete a task.
  3. Units - In MSP, "units" is (sort of) equivalent to "no. of resources"

Following formula provides a rough relation between these three terms:

Work = Units * Duration

As per the wording of your Q, it looks like 184 hours is "effort" and one month is "duration". In your case "units" is 5-6 resources.

MSP provides 3 different options for task scheduling -

  1. Fixed Work - The work (184 hours) would not change if you change one of the other 2 parameters
  2. Fixed Units - The units (5 resources) would not change if you change one of the other 2 parameters
  3. Fixed Duration - The duration (1 month) would not change if you change one of the other 2 parameters

To understand which option you are using, you should use the "task details" dialog. You can also use "work" and "duration" column in "gantt chart view" of MSP to see the relationship.

Hope it helps.


Firstly ensure the task is "Auto Scheduled", then make sure that the "Effort Driven" box is checked. This means that as you add or subtract resources (assuming it is not set to Fixed Duration) the elapsed time will move accordingly.

  • Thank you, and the task should be Fixed Work? Fixed Units?
    – user23439
    May 16, 2016 at 14:48
  • From your description, Fixed Units, though you should research your own understanding of how MS-Project works. See here: support.office.com/en-us/article/…
    – Marv Mills
    May 16, 2016 at 16:54

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