Absence Rates Project Time (Individual) Calculator FAQ
Answers to common questions about estimating individual project time, absence allowances, workdays and scheduled hours.
Use these questions and answers to understand what the calculator estimates, which inputs it uses, and where further schedule planning may be needed.
General questions
Basic information about absence-adjusted individual project planning.
What does the Absence Rates Project Time (Individual) Calculator do?
It estimates the scheduled working days and hours one person may need to complete a defined amount of productive work after allowing for an expected absence rate.
Who is this calculator for?
It is intended for planning work assigned to one individual where an availability allowance is needed.
What is an absence rate in this calculation?
It is the percentage of scheduled work time expected to be unavailable because of sickness, appointments, leave, or other absences included in the planning assumption.
Is the result measured in calendar days?
No. The main result is scheduled working days. Convert it to a calendar date using the actual working calendar.
Inputs and calculation
How planned work, absence and daily hours are used.
What should I enter as planned productive work days?
Enter the days of actual productive effort the project would require if the person were fully available.
How is expected attendance calculated?
Expected attendance equals 100% minus the expected absence rate.
How are adjusted project days calculated?
The calculator divides planned productive work days by the expected attendance rate expressed as a decimal.
What does total scheduled hours mean?
It is absence-adjusted project days multiplied by working hours per day, including hours expected to be unavailable.
Accuracy and assumptions
Factors that can cause actual delivery time to differ from the estimate.
How accurate is an absence-adjusted project-time estimate?
It is an estimate based on the inputs and the assumption that absence occurs evenly. Actual results can differ.
Should I use historical absence data?
Recent, relevant information can be a useful planning input where available, but the chosen rate should reflect the project period and working arrangement.
Does the calculator allow for public holidays and weekends?
No. Add those non-working periods separately when translating working days into a delivery date.
Does it account for lower productivity after absence?
No. It assumes productivity is unchanged during available working time.
Using the result in a project schedule
How to interpret the outputs alongside broader project planning.
What is the extra time to allow output?
It is the additional scheduled working days caused by the expected absence allowance.
Should I add other project contingency to this result?
This calculator only estimates absence-related time. Other uncertainties, such as dependencies or approval delays, should be considered separately where relevant.
Can I use this calculator for a team project?
It is designed for one person. Team work may need separate availability assumptions and dependency planning for each contributor.
What if the project has a fixed delivery date?
The result can help compare planned effort with available scheduled work time, but it does not determine whether the date is achievable.
How does absence affect an individual project timeline?
When part of scheduled time is unavailable, more working days are needed to achieve the same productive work requirement.
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