Others

How to Prevent Duration and Work from Changing in Microsoft Project

Nimra Malik Oct 10, 2026 871 views

Question details

The user wants to stop Microsoft Project from automatically altering a task's planned duration and work hours when new resources are assigned.

How to Prevent Duration and Work from Changing in Microsoft Project

Product: Microsoft Project
Device & OS: not provided
Scenario: Assigning resources to tasks during project schedule development or modification.
Observed behavior: Microsoft Project recalculates Work and Duration automatically based on task type, assignment units, and effort-driven scheduling settings, which alters the originally planned schedule.

Before you start

Before adjusting task settings, ensure you understand the scheduling formula (Work = Duration × Units) used in Microsoft Project, as locking one variable will force the software to recalculate the others when changes are made.

Solution 1Recommended

Set Task Type to Fixed Duration and Disable Effort Driven

This method ensures that adding or removing resources will not change the planned duration of your task.

Microsoft Project uses three task types: Fixed Units, Fixed Duration, and Fixed Work. By default, tasks are set to Fixed Units. To lock the duration so it does not shrink or expand when you add people to the task, you must change the task type to Fixed Duration and turn off effort-driven scheduling.

Open Task Information

Double-click the target task in your Gantt chart view to open the "Task Information" dialog box.

Navigate to Advanced Settings

Click on the "Advanced" tab at the top of the dialog box.

Change the Task Type

Locate the "Task Type" dropdown menu and select "Fixed Duration".

Disable Effort Driven

Uncheck the "Effort driven" box located just below the task type setting, then click "OK" to apply the changes.

Understanding the Change: With Fixed Duration and Effort Driven disabled, adding another resource will increase the total Work allocated to the task while keeping the overall Duration unchanged.

Solution 2

Set a Baseline to Track Schedule Changes

If you need to allow dynamic scheduling but want to preserve the original plan for comparison, setting a baseline is the best approach.

Free Microsoft Office alternative

Manage Projects Seamlessly with WPS Office

While Microsoft Project is a specialized tool, many project management tasks, schedules, and Gantt charts can be effectively managed using spreadsheet software. WPS Office offers a free, lightweight, and highly compatible alternative to Microsoft Office, providing powerful Spreadsheet capabilities to track tasks, durations, and resources without complex automatic recalculations.

1. Download WPS Office: Visit the official WPS website and download the free WPS Office suite.
2. Open WPS Spreadsheet: Launch the application and open WPS Spreadsheet to access free project management templates.
3. Customize Your Tracker: Input your tasks, manual durations, and resource assignments to track your project with complete manual control.

Easily create customized Gantt charts and project trackers without a steep learning curve.Fully compatible with Microsoft Excel formats (.xlsx, .xls) for seamless file sharing.Free, lightweight, and fast-loading office suite.Familiar, tabbed user interface makes migration effortless.

microsoft office alternative - wps office

Frequently Asked Questions

What does "Effort Driven" mean in Microsoft Project?

Effort-driven scheduling assumes that the total work required for a task remains constant. If you add more resources to an effort-driven task, the duration will automatically decrease because the work is distributed among more people.

What is the default task type in Microsoft Project?

By default, Microsoft Project sets tasks to "Fixed Units" with "Effort driven" disabled. This means if you add a resource, the total Work increases, but the Duration stays the same.

How do I change the default task type for all new tasks?

Go to File > Options > Schedule. Scroll down to the "Scheduling options for this project" section, and change the "Default task type" dropdown to your preferred setting, such as Fixed Duration.

Why did my task duration change when I manually edited the work hours?

If your task is set to "Fixed Units" (the default setting), Microsoft Project calculates Duration as Work divided by Units. Therefore, manually increasing the Work value will automatically force the Duration to increase as well.

Office Quick Solutions