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What is ‘human effort’ (person-months) and how to calculate it?

‘Human effort’ (person-months) is the metric for the time (effort) that the key personnel of an organisation devotes to a specific project.

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Justice and Consumers

date:  05/02/2019



We need an accurate calculation of ‘human effort’ to evaluate the relationship between the estimated work to be performed and the scale, type and number of activities and deliverables to be achieved during the implementation period.

NB: estimated staff costs must correspond to normal salary rates (documented by salary grids, long-term work contracts, etc.) and cannot significantly exceed the rates generally applicable in the relevant geographical area and for the staff profiles in question (as required for the project).


If you want to submit a proposal, you will need to fill in a template. The proposal template is composed of two main parts: Part B (technical content of the proposal) and Part A (administrative information and estimated budget of the project).

In Part B, all participants have to assign the effort (person‑months) to each work package and this must be consistent with each organisation’s direct personnel (staffing) costs. 

The total of the estimated costs by cost category in Part B must be consistent with the amounts in the ‘budget overview table’ in Part A. The electronic submission system does not automatically reconcile the various budget tables in the proposal; it is the applicant’s responsibility to ensure the consistency of the information provided across the whole proposal package.


The estimated human effort by work package in Part B can be calculated as follows (indicative method): if 1 year = 220 (working) days, then 1 month = 220/12 = 18.33 (working) days. So 24 full working days for one person would be 24/18.33 = 1.31 person‑months.

To calculate the total person‑months, multiply the proportion of your effort associated with the project by the number of months of the appointment.  


A project implemented over 24 months involves four organisations with the following staff: 

  1. the coordinating organisation employs a project manager working full time on the project for the entire duration (24 months);
  2. each of the other three beneficiaries employs a project manager working a quarter of their time on the project for the entire duration;  
  3. the coordinating organisation also employs a financial project manager/accountant working 1/10 of their time on the project; and
  4. five researchers (covered by category A of the budget) each work on the project for 1/6 of their time starting after the first six months and continuing for a year (i.e. months 7‑18 of the project). 

The project effort in person‑months would be calculated as follows: 

  1. 24 person‑months;
  2. 6 person‑months for each of the three beneficiaries, i.e. 18 person-months;
  3. 2.4 person‑months;
  4. 2 person‑months for each researcher (1/6 x 12 person‑months) x 5 = 10 person‑months.
Total project effort: 24 + 18 + 2.4 + 10 = 54.4 person‑months
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