Estimate Activity Resources – How To Estimate Resources In The Project?

Estimate activity resources process in time management knowledge area tell us about the resource requirements for the activities.

Broadly resources could be of two types.

  • Human resources – Human resources are the people who work on the project.
  • Physical resources – these could be machinery, tools, software, hardware, etc…

Meaning that estimate activity resources is all about analyzing

  • how many people would be required to complete each activity from the activity list,
  • skill set and other criteria for each resource
  • when the resources need to available to complete the activity,
  • and any other constraints or information about the resource pertaining to the activity
  • Finally what other non-human resources required, availability, etc.

This process primarily focuses on the resource availability angle for each activity with an input that we will discuss in a while called resource calendar.

When this activity needs to be done?

As soon as you have the activity list and their attributes from define activities process, you can start the estimate activity resources process.

Estimate activity resources process

Estimate Activity Resources Process

The primary idea of this process is to assess

  • suitable resources and their availability for each of the activities of the project
  • quality and quantity of such resources
  • check and plan for alternatives when some of the resources not available for project to use

The following are the ITTOs of estimate activity resources process.

InputsTools & TechniquesOutputs
  • Schedule management plan
  • Activity List
  • Activity Attributes
  • Resource Calendars
  • Risk Register
  • Activity Cost Estimates
  • Enterprise environmental factors
  • Organizational process assets
  • Expert Judgement
  • Alternative Analysis
  • Published estimating data
  • Bottom-Up Estimating
  • Project Management Software
  • Activity Resource Requirements
  • Resource Breakdown Structure (RBS)
  • Project Document Updates


Schedule management plan

Schedule management plan will describe the approach of how the other processes of time management knowledge are should perform.

In this case schedule management plan will provide methods of how to estimate activity resources and what is the level of accuracy of these resource estimations.

Activity List

Although we have already seen that activity list is an important output of define activities process, it is also an important input to the estimate activity resources process. Activity list contains the list of activities that the project comprise of.

For each activity in the activity list, the resource requirements are evaluated as part of estimate activity resources process.

Activity Attributes

Activity attributes are additional information about the activity. So whenever you use activity, you would also need to activity attributes to understand more about the activity. For example activity attributes can be the predecessor, successor, and any constraints on that activity, etc.

Resource Calendars

Resource calendars are another primary input to estimate activity resources process. As we have seen earlier, resources can be either physical resource or a human resource. Irrespective of the resource type, resource calendar provide the resource availability information.

For example a machine, tool or  a principle architect required for the project is only available during a specific period of time. So in this cases the project should consider these resource constraints, while estimating the resource requirements for the project.

Risk Register

Risk register contains all the risks that are identified in the project to that point in time. In this context, if there are any risks associated with the resources, the project needs to consider those risks, while planning those resources for the activities.

Activity Cost Estimates

Usually we estimate the cost of the activity after the resources and efforts are identified for that activity in bottom up estimation model. However in some cases, the cost of the activities are already fixed, then those needs to be used when estimating activity resources process to determine the resource requirements.

Enterprise Environmental Factors

Enterprise environmental factors are part of common ITTO s for many project management processes. Please read the blog post on common ITTO s for more details.

In this context, your organization might have policies or procedures of which type of resources needs to use, how to get access to a certain type of resources, etc. This type of information is useful in estimating activity resources process to determine the resources for the project activities.

Organizational process assets

Organizational process assets are a common ITTO s for many project management processes. Please read the blog post on common ITTO s for more details.

In the estimate activity resources process, you can refer to the estimate activity resources process in the similar historical projects. Also lessons from historical projects are also help for resource selection, if any.

Tools & Techniques

Expert Judgement

Taking expert or SME opinion, who did the similar activity in the past will help in the estimate activity resources process. Expert judgement is again a common ITTO. Please read through blog post on common ITTO s for more details.

Alternative Analysis

Alternative analysis will always help in finding the best. This is even true in this process. Also when a specific resource is not available, then the project may need to consider other best alternatives available which suits your project needs.

Published estimating data

Indeed some industries publish standard estimating information which are of great help in the estimation process. Eventually this information publishes in authorized journals, websites, publications, etc.

For example, the blended rate per hour for a human resource in a system integration point is around 80$ in US in the telecom industry. This kind of information often useful when estimating the resources.

Bottom-Up Estimating

Eventually when you have a complex activity or task which is difficult to estimate, you then break down this task into multiple levels to simplify the complex task. Then you start estimating for each activity. And then finally you roll up the estimates for all the activities to come up with estimation for the top level activity. This is called bottom-up estimation.

Project Management Software

A project management software often helps you to play with resource alternatives and see, how the project looks with each alternative. The project management software like Microsoft project or open project will help with different resources with varied set of parameters for each resource to see how they fit into the project.


Activity Resource Requirements

The primary output of the estimate activity resources process. Activity resource requirements should specify following things primarily.

  • What type of resources require for activity?
  • How many of such resources required?
  • The duration of each resource as per the need.

It should also document the justification or basis for resource estimation.

Resource Breakdown Structure (RBS)

The resource breakdown structure (RBS) is about a graphical representation of logical resource hierarchy from top to bottom. A hierarchical chart organizes resources by a logical classification of resources.

In many ways RBS is very similar to work breakdown structure (WBS). Remember that work breakdown structure (WBS) is an output of define scope process of scope management knowledge area.

Project Document Updates

Project Document Updates is a common ITTO for many PMP processes. Please read the blog post on Common ITTO s for more details.

In estimating activity resources, you may see updating the activity list, activity attributes, resource calendars to name a few. So updates might require to the activity list and attributes with more information about the activity, if any. Also you may need to update resource calendar with tentative timelines information of the resource if you know in advance.


To conclude with, estimating activity resources is a process of determining and estimating the resource availability for each activity in the project. If we see the order, we started with scope baseline, then defined the activities in the project and then determining the resources for each activity in the project.

Furthermore, the next process is to determine the activity duration for each activity based on the resource estimation provided in this process.

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