Resource Leveling: Scheduling vs. Leveling

“Don’t click the level button — it messes up your schedule.” How many times have you said this or heard it? If I had a nickel for each time I’ve heard this over the course of 25-plus years, well, let’s just say I’d be a wee bit closer to a comfortable retirement. There’s a truth in that statement. Microsoft Project will mess up your schedule — if you don’t understand what leveling does or how it works.

Sometimes we forget that Project is only a software tool, albeit a complicated one. It has no perception of time and therefore doesn’t understand concepts like today, the past or the future. It only has algorithms. And it doesn’t understand what we “want” it to do; it only does what we “tell” it to do. As a result, the ownership is on us, the human, to learn how Project works and what the available options do so that we can “tell” Project the right things to get the results we “want.”

Resource leveling — or just “leveling” as it’s more commonly known — is probably the most complicated, feared and misunderstood functionality within Project. It takes a long time to learn and the learning process is often a series of anxiety-filled experiments that end up creating more frustration than understanding. And because project managers actually have projects to run (who knew?), they typically don’t have time to experiment. The result; “Don’t click that button…”

It’s time to change that.

This is the first in a series of articles focused on resource leveling. The series objective is simple; to uncloak the mystery that is resource leveling and help you, the project manager, transition from fighting the tool to controlling the tool. To accomplish the objective this series includes articles covering the following general topics:

  • Laying a foundation, including scheduling vs. leveling and problem indicators and what they’re telling you;
  • A deep dive into how leveling works, including leveling mechanics (what to level and when);
  • Leveling hierarchy, covering which task stays and which task moves;
  • Resolution options — ways to resolve overallocations and limitations;
  • Leveling a schedule such as preparing to level, the leveling functions and the leveling cycle; and
  • Leveling guidelines.

Want more? Watch Daryl Deffler’s two-part webinar series on resource leveling, now available, on demand.

Read Daryl’s articles in this resource leveling series here:
“Scheduling vs. Leveling”
“Problem Indicators”
“Leveling Mechanics”
“Leveling Hierarchy, Part 1”
“Leveling Hierarchy, Part 2”
“Resolution Options”
“Understanding Split Task Options”
“Leveling Fields”
“Preparing to Level”
“Resource Leveling: It’s Time to Level Your Schedule”
“Resource Leveling: The Leveling Cycle”
“Resource Leveling: Recommendations”

Also, download a resource leveling “cheat sheet” in PDF format!

Scheduling vs. Leveling: An Overview

Scheduling and leveling are two distinct foundational concepts within Project. They’re as essential as formula calculations are to Excel. In essence, they’re the primary reason for Project; to automate the process of sequencing project tasks while making the most effective use of available resources.

Scheduling is timeline-oriented, focused on creating the absolute shortest schedule duration. It occurs when the Calculate Project icon is clicked. Or, if you’re like many project managers who turn on the “Calculate project after each edit” option, scheduling occurs automatically after every change.

Leveling is resource-oriented, focused on making the most effective use of available resources. It occurs when one of the leveling icons such as Level All is clicked. If the Leveling option “Leveling calculations” is set to Automatic, it can also occur automatically, after every change is made.

What does “timeline-oriented” and “resource-oriented” mean? The following sequence provides a simple illustration of how scheduling and leveling work. For this sequence automatic scheduling and leveling have been turned off.

The project manager creates Tasks 1 through Task 3 with no relationships as illustrated below. Resource A is overallocated on the first three days.

In the second screen, below, the project manager defines Task 1 as the predecessor to Tasks 2 and 3. Notice that even though the relationships have been established, nothing has changed.

The project manager clicks the Calculate Project button and the results are shown below. Tasks 2 and 3 are shifted later in the timeline because they’re Task 1 successors. But notice Tasks 2 and 3 start on the same day, even though this overallocates the resource. The reason is simple: Scheduling is focused on sequencing the tasks to create the absolute shortest possible duration. Starting Tasks 2 and 3 on the same day doesn’t violate any dependency relationship, but it does result in the shortest possible duration, regardless of resource impacts.

In the final sample, below, the project manager clicked Level All. At this time, leveling, which is resource-oriented, delayed Task 3 to start after Task 2. This was done not because of any dependency relationship between Tasks 2 and 3, but because the first availability for the resource was the following Friday.

The following table provides a summarized comparison of both scheduling and leveling.


Primary FocusEffectively using the timelineEffectively using available resources, which in most but not all cases is removing resource overallocations
Will move tasks?Moves tasks in both timeline directions, based on task or dependency changesOnly delays tasks from the scheduling-defined start or resume date
Adjusts task duration?May adjust duration based on changes to a predecessor taskMay extend calendar duration, but only if "Leveling can create splits in remaining work" option is checked
Can split a task?Yes, will split all remaining work from actual work if the scheduling option "Split in-progress tasks" option is checkedYes, will only split remaining work after the scheduling-defined resume date if the "Leveling can create splits in remaining work" option is checked
Fixes resource overallocations?No. Scheduling results will often create resource overallocationsYes. But may not fix all over allocations

Note: Task-level adjustments such as changing work, resource assignment units or duration adjust the individual task immediately, regardless of the automatic schedule or level option selections.


As tempting as it might be to set both scheduling and leveling to occur automatically, I don’t recommend this. My suggestion: Configure scheduling to occur automatically and leveling to occur manually.

This is recommended for several reasons. Performing both processes automatically blurs the process boundaries, and as a result it becomes difficult to determine if an issue appeared during scheduling or leveling. Performing these processes separately helps resolve issues at a high level. If the issue appears after scheduling (before leveling), it’s task related (task configuration, task dependencies, etc.). When the issue appears after leveling, it’s resource related.

Additionally, Microsoft recommends executing these processes separately to enable better tool performance and to produce better results.

Next time: Learn about resource leveling indicators.

Written by Daryl Deffler
Daryl Deffler is currently employed by a large insurance company where he provides project management, project scheduling tool, process, and standards consulting for an enterprise project management office comprised of about 200 project managers. He has over 25 years in the IT project management field with experience managing small projects to large programs. During this time he has also developed and taught classes in both project management and scheduling tools such as Microsoft Project 2013, Primavera and ABT Workbench. He has been employed in the IT industry since 1979 in additional roles, including software development, technical support and management across mainframe, midrange and PC platforms.
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  1. Thanks for the first instalment in this series Daryl. Eagerly awaiting the subsequent articles in your series!

  2. The schedule images in the article use the Task Usage view.
    All tasks are Auto Scheduled, rather than Manually Scheduled.
    The Resume date is a column than can be inserted in a table or column’s formula.
    When leveled, Task 3 is delayed past Task 2 because the leveling algorithm starts a longer task before a shorter task.

  3. Scheduling can change a task’s duration if its resource’s Assignment Units is changed, not it’s predecessor.

  4. Thank you for adding more insight into my understanding of project management. A new layer learning about levels was welcome.

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