Absence Rates Project Time (Annual) Calculator FAQ
Answers to common questions about annual absence rates, lost project hours, available capacity, person-days, and FTE results.
Use these answers to understand the inputs, calculation method, and practical limits of annual absence-based project capacity estimates.
General questions
Basic information about what the calculator estimates and how it can be used.
What does the annual absence project time calculator estimate?
It estimates annual project hours lost to absence, project hours remaining, lost person-days, and the average FTE capacity represented by the absence rate.
Who can use this calculator?
It can be used by project teams, managers, workforce planners, and anyone estimating how expected absences may affect planned team capacity.
Is the result a forecast of actual absence?
No. It is a planning estimate based on the annual absence rate and working pattern entered.
Can the calculator be used for a whole department?
Yes, provided the inputs reasonably represent the people and project time being assessed. Separate calculations may be clearer for groups with different schedules.
Inputs and calculation method
How each input affects the annual project-time calculation.
How are planned annual project hours calculated?
Team size is multiplied by working days per employee and project hours per working day.
How are absence hours calculated?
Planned annual project hours are multiplied by the absence rate divided by 100.
What should I enter for working days per employee?
Enter planned annual working days after known non-working days, such as planned leave and public holidays, have been removed.
What should I enter for project hours per day?
Enter the average productive hours each person is planned to spend on the project during a working day.
Can I enter an absence rate of zero?
Yes. A zero rate produces no estimated absence loss, although real-world plans may still require contingency for unexpected disruption.
Understanding results
How to interpret the four main outputs.
What are available annual project hours?
They are the planned annual project hours left after the estimated absence hours have been deducted.
What is meant by project days lost?
It is the estimated lost project time expressed as person-days, calculated using the project hours entered per day.
What does FTE capacity lost mean?
It translates the annual absence percentage into an average full-time-equivalent share of the team. For example, 5% across 10 people equals 0.5 FTE.
Can available project hours be used directly as a delivery commitment?
They are an estimate of capacity, not a delivery guarantee. Scope, dependencies, skills, interruptions, and the timing of absences can affect delivery.
Accuracy and planning limits
Factors that may cause actual capacity to differ from the estimate.
Why can actual absence impact be different from the result?
Absences may vary by season, role, individual circumstances, and timing. Operational work, turnover, training, and workload changes can also affect capacity.
Does the calculator include overtime or temporary cover?
No. It only reduces planned hours by the stated absence rate unless you adjust your inputs to reflect other capacity assumptions.
Does the calculator account for critical skills or role coverage?
No. It measures total time only. The absence of a key role can affect a project more than the annual hours calculation suggests.
Should I use one absence rate for every team?
Use a rate that is appropriate for the group and planning period being considered. Different teams can be calculated separately where their working patterns differ.
How are project hours lost to absence calculated?
Multiply planned annual project hours by the annual absence rate divided by 100.
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