Create a Custom Field to Calculate Percent Duration Variance in Microsoft Project

Hey there! In this blog post, I’ll guide you through the process of creating a custom field in Microsoft Project that will help you calculate Percent Duration Variance for each task. This handy feature allows you to easily understand and visualize how your project tasks are progressing in relation to their Baseline Duration values.

If you would rather watch a YouTube video on this subject, click here or click the thumbnail below.

Percent Duration Variance

Percent Duration Variance Calculation: How Does it Work?

Before we dive into creating the custom field, let’s briefly talk about how Microsoft Project calculates Duration Variance. It’s quite simple. Duration Variance is calculated as the current Duration of each task minus the Baseline Duration. For example, if a task has a current Duration of 15 days and a Baseline Duration of 10 days, the Duration Variance would be 15 days minus 10 days, resulting in 5 days of Duration Variance.

To calculate the percent of Duration Variance, we use the following formula:

Percent of Duration Variance = 100 x (Duration Variance/Baseline Duration)

To create the preceding formula in a custom field in Microsoft Project, it is absolutely crucial to account for tasks with no Baseline saved and for tasks that are milestones to avoid division by zero errors. Now, let’s get started with creating the custom field.

Creating the Custom Field

To create the custom field, complete the following steps:

  1. Click on the Project tab to display the Project ribbon.
  2. Click the Custom Fields button in the Properties section of the ribbon.
  3. In the Custom Fields dialog, select the Number type from the Type pick list.
  4. Choose an available Number field, such as Number 1, and click the Rename button.
  5. In the Rename Field dialog, name it something short like “Percent Dur Var” and then click the OK button.

Creating the Formula

To create the custom formula to calculate the percent of Duration Variance, complete the following steps:

1. Click the Formula button in the Custom Fields dialog.

2. Use the field names and operators to build the following formula. You can also copy and paste the formula, if needed.

IIf([Baseline Estimated Finish] = ProjDateValue(“NA”), -16000, IIf([Milestone], 0, 100*([Duration Variance]/[Baseline Estimated Duration])))

3. Click the OK button to save the formula.

The preceding formula initially tests for tasks with no Baseline saved and then tests to determine if the task is a milestone. If both tests are false, then the formula calculates the percent of Duration Variance for the task.

Configuring Graphical Indicators

To add graphical indicators to the custom field, complete the following additional steps:

1. Click the Graphical Indicators button in the Custom Fields dialog.

2. In the Graphical Indicators dialog, set up graphical indicators based on your organization’s criteria. For example:

  • If Duration Variance > 100%, display a red unhappy face.
  • If 50% ≤ Duration Variance < 100%, show a red stoplight.
  • And so on… Customize the criteria to match your project management processes.

3. Select the “Show data values in Tooltips” checkbox and then click the OK button to save the graphical indicators.

4. Click the OK button to close the Custom Fields dialog and to save the new custom field.

Saving the Custom Field for Future Projects

Complete the following steps to save this new custom field so that you can use it in all current and future projects:

  1. Click the File tab, click the Info tab in the Backstage, and then click Organizer to display the Organizer dialog.
  2. In the Organizer dialog, click the Fields tab.
  3. In the list of custom fields on the right side of the dialog, select your custom field.
  4. Click Copy to copy it into your Global .MPT file for use with all current and future projects.
  5. Click the Close button to close the Organizer dialog and then press the Escape key on your computer keyboard to exit the Backstage.

And that’s it! You’ve successfully created a custom field for percent Duration Variance in Microsoft Project. Now, your project tasks will visually indicate their progress, helping you stay on top of your project timelines.

If you have questions, please add them in the “Leave a Reply” section below. Or if you watched the video, add your questions or comments there. Please subscribe to my YouTube channel and leave “Likes” if you like the videos.

If you would like to have a formal class on using Microsoft Project, here is a link for my classes.

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Course Materials

As a part of this course, each student will receive the following:

  • Hands On Exercises workbook in PDF format
  • Student sample files

Course Description

This “hands on” self-paced eLearning course teaches the foundational knowledge required to effectively manage “process agnostic” enterprise projects using Microsoft Project with either Project Online or Microsoft Project Server. Our “keep it simple” training approach allows students to master the vital skills they need to effectively plan and manage an enterprise project using Microsoft’s PPM (Project Portfolio Management) tools.


This course is focused on the core needs of project managers, project schedulers, and project coordinators who use Microsoft Project with either Project Online or Microsoft Project Server to manage enterprise projects.

Course Pre-Requisites

Each student must have a copy of one of the following installed on his/her PC:

  • Project Online Professional for Office 365
  • Microsoft Project 2016 or higher

Versions of Microsoft Project earlier than the 2016 version do not qualify for this course.

Best Instructor Ever!

Dale Howard has been a Microsoft Project MVP (Most Valuable Professional) for 20 years in a row and is currently one of only 26 Project MVPs in the entire world. If you post a question about any of Microsoft’s PPM tools on the public message boards, Dale is frequently the person who will answer your question.

Module 01: Microsoft Project Overview

  • Working with the User Interface
  • Understanding the Gantt Chart View
  • Understanding the Microsoft Project Data Model
  • Understanding and Using Views
  • Understanding and Using Tables
  • Understanding and Using Filters
  • Understanding and Using Groups
  • Project Navigation Tips

Module 02: Working with a New Project

  • Creating a New Project
    • Creating a New Project from a Template
    • Creating a New Project from a Personal Template
  • Working with the Standard Calendar
    • Add Holidays to the Standard Calendar
    • Create a Custom Calendar
    • Copy Calendars to the Global.mpt File
  • Defining a New Project
    • Set the Project Start Date
    • Enter Project Properties
    • Display the Project Summary Task
    • Set the Project and Nonworking Time Calendars
    • Set Project Options
    • Save the Project

Module 03: Task Planning

  • Understanding Manually Scheduled vs. Auto Scheduled Tasks
  • Creating the Task List
  • Creating Summary Tasks
  • Creating Milestone Tasks
  • Entering Duration Estimates
  • Specifying Task Dependencies – Overview
  • Specifying Task Dependencies in a Real World Project
  • Applying Task Constraints
  • Applying Deadline Dates
  • Applying a Task Calendar
  • Using Cell Background Formatting to Highlight Tasks of Interest

Module 04: Resource Planning

  • Understanding Project Resource Types
  • Creating a Work Resource
  • Creating a Generic Resource
  • Editing a Work Resource
  • Creating a Material Resource
  • Creating Budget and Expense Cost Resources

Module 05: Assignment Planning

  • Assigning Resources to Tasks: Best Practices
  • Assigning Resources to Tasks Using the Task Entry View
  • Assigning Resources to Tasks Using the Assign Resources Dialog
  • Assigning Material Resources
  • Assigning Budget Cost and Expense Cost Resources

Module 06: Completing the Project Schedule

  • Performing a Quality Check on the Project Schedule
  • Saving and Backing Up a Baseline for the Project

Topical Outline: Execution Training

Module 07: Capturing Task Progress

  • Setting the Status Date for the Project
  • Manually Entering Task Progress

Module 08: Working with Task Updates

  • Rescheduling Incomplete Work from the Past

Module 09: Variance Analysis, Plan Revision, and Change Control

  • Analyzing Project Variance
  • Revising a Project Schedule
  • Adding New Tasks to a Project through Change Control
  • Updating the Project Baseline

Module 10: Project Reporting

  • Creating a Timeline View
  • Formatting the Timeline View
  • Exporting the Timeline View to Another Application
  • Viewing a Dashboard Report
  • Editing a Table in a Dashboard Report
  • Editing a Chart in a Dashboard Report

Microsoft Project Training Course Samples

Click here to see some of the videos from the courses or check out my YouTube Channel for tips and tricks about Microsoft Project, Project Online/Server and Project for the Web.

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