There are a number of factors that dictate how Microsoft Project “thinks”.

The two main factors are:

- The Scheduling Formula
- The Task Type

The scheduling Formula leverages three variables:

- Units – The percentage of time required by a resource or resources to complete the task
- Duration – The number of working days required to complete the task
- Work – The effort required to complete the task

e say that the scheduling formula is: Units x Duration = Work

When you initially assign a Resource to a Task, this is the formula that is leveraged. Let’s demonstrate:

We will create Task 1 that is 5 days in Duration

We will now assign a Resource to this task

As soon as we assign this Resource to this task, Work changes to 40 hours.

Here is the how that number was calculated:

Units x Duration = Work

100% x (5*8) = 40

Or

100% x 40 = 40 hours

But using simple math, we can re-write our equation to solve for a different variable.

Our original formula solves for Work:

Units x Duration = Work

But we could re-write the formula to solve for Units:

Work / Duration = Units

Or we could re-write the formula to solve for Duration:

Work / Units = Duration

So we have shown that The Scheduling Formula can actually be written three different ways:

Units x Duration = Work

Work / Duration = Units

Work / Units = Duration

Now let’s prove that Microsoft Project also thinks this way.

In order to demonstrate this, we must introduce The Task Type or the **Type** field:

By default, Type is set to Fixed Units. But there are actually three different Task Type variables:

- Fixed Duration
- Fixed Units
- Fixed Work

Now to test Microsoft Project

Using our original scenario, let’s force Microsoft Project to solve for **Duration**.

We will leave Type set to Fixed Units and change Work to 80 hrs

Here is how **Duration** was calculated:

Work / Units = Duration

80 / 100% = 80

Or

80 / 100% = (80 /

Or

80 / 100% = 10 days

Returning to our original scenario, let’s force Microsoft Project to solve for **Work**.

Leave Type set to Fixed Units and enter 10 days Duration

Here is how **Work** was calculated:

Units x Duration = Work

100% * 10 days = 80

Or

100% * 10 days = (10 *

Or

100% * 10 days = 80 hours Work

Returning to our original scenario, let’s force Microsoft Project to solve for **Units**

Change Type to Fixed Duration and enter 20 hours Work

Here is how **Units** was calculated:

Work / Duration = Units

20 / 5 days = 50%

Or

20 / 5 days = 20 / (8 * 5)

Or

20 / 5 days = 20 / 40

Or

20 / 5 days = 0.5

The Task Type and Scheduling Formula Cheat Sheet will help you control how Microsoft Project “thinks”: