How do you calculate the number of resources in a project? 

Resource management is the fundamental pillar of any successful project portfolio. In project management, human resources play a key role. As Geopost's CIO said in his speech at VIRAGE Days, "It's all about HR...". While money is important, finding talent is more difficult. So it's essential to allocate resources wisely and optimize needs. This is especially true when managing a large number of projects in parallel. Whether or not a project can be launched, paused or prioritized depends largely on the resources available. Correctly sizing resources is therefore an essential part of project portfolio management.  

How do you calculate the number of resources needed for a project? Or, to put it another way: how many resources must be mobilized to achieve the expected results for each project? This question highlights the importance of finding the right amount of resources to invest in each project, which is at the heart of portfolio management. 

In this article, we will highlight the crucial importance of calculating the number of resources needed to complete projects. We'll explore the key steps involved in making this assessment accurately. 

Find out more in this article:

How to evaluate project resources?

The calculation of project resources does not follow a linear or sequential process. It depends first and foremost on the phase the project or project request is at. In fact, estimating the resources required starts with an overview when the project request is submitted, and becomes more precise as the project progresses. 

1. Request

Calculation of resource requirements for project applications

Evaluation of new project applications by committee

  • Creation of a requirements form
  • Identifying the skills needed
  • Estimated volume of resources required

2. Launch

project launch

Precise estimation of resource requirements

  • Calculation of the workload for each stage, or calculation of the overall project workload based on an estimate of the project development workload.
  • More detailed estimate of skills required
  • Allocation of resources according to availability: in-house or outsourced

3. Realization

Regular reassessment of project resource requirements

Regular reassessment of resource requirements

  • Taking into account changes in scope or deadlines
  • Estimated readjustment requirements

4. Closing and balance sheet

Analysis of time spent by resources

Capitalizing on learning

  • Analysis of time spent by resources
  • Updating load charts
  • Estimate/actual comparison

Steps to help you calculate project resource requirements

1. Overall estimate of skills required

Before determining the number of resources required, it is essential to have a clear understanding of the project's objectives and requirements. When formulating the project idea, the requester specifies the framework and objectives of the project, so that the decision-maker can identify the overall skills required. A needs expression sheet is created for this purpose. 

2. Estimating the volume of resources required (analogy, charts) 

The decision-maker calls in experts and may appoint a provisional project manager to estimate the volume of skills required. This estimate can be based on analogies or load charts. It helps determine whether or not the project can be launched. 

3. Precise estimation of resource requirements

Once the project application has been validated, a more detailed skills assessment is carried out. This involves identifying the skills, expertise, qualifications and experience required to complete the project. It also involves determining the availability of "talents" and assigning them to the various phases of the project, while beginning to plan the project. Depending on the availability of resources, decisions on staffing, subcontracting and prioritization need to be made. 

4. Regular reassessment of resource requirements  

During project execution, resource requirements change according to changes in scope or deadlines. It is therefore essential to regularly reassess estimates and adapt accordingly. 

5. Capitalizing on learning: Project closure

Closing the project provides an opportunity to capitalize on the lessons learned. These lessons will serve as a reference for similar projects, and will be used to update the load charts. 

Some calculation methods for estimating project costs and lead times

Calculate minimum and optimum project completion times

Tmin (in months) = 2.5 * (load in man-months)^1/3 (exponent 1/3 = cube root)

Estimate the optimum resources required to complete the project

The number of resources is a function of the square root of the load in man-months.

Number of resources = (expenses in man-months)^1/2

So, for a project estimated to take 240 days, or 12 man-months, you'll need 3.5 full-time equivalents.

Which tool can help you plan project resources?

Calculating the number of resources needed for a project is an evolving, iterative process that requires careful planning and a clear vision of objectives. 

To facilitate this process, we suggest you explore the usefulness of Project Portfolio Management (PPM) software such as Project Monitor. With Project Monitor, you benefit from advanced tools for managing project requests, creating intention sheets from predefined templates, planning both generic and specific resources, and tracking project execution in real time.  

By adopting these steps and taking advantage of Project Monitor's features, you'll be able to calculate more accurately the resources needed to make your project a success, while successfully achieving your objectives. Find out how Project Monitor can optimize your project management processes today. 

Other frequently asked questions about resource management

What is the load factor?

Who allocates resources to the project?

What resources are needed to make a project a success?

How do you calculate a project's workload?

How to distribute the workload?

How do you smooth out the workload?

How to draw up a successful workload plan to effectively manage project resources?

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