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Absence Rates Project Time (Annual) Calculator

Estimate the annual project time lost to employee absences and the remaining available team capacity.

Your Details

Overview

This annual absence rates project time calculator estimates how many planned project hours may be lost when a team has an expected absence rate. Enter your team size, annual working days, daily project hours, and absence percentage to see the capacity likely to remain for project work.

How it works

The calculator first multiplies team size by planned working days and project hours per day to find total annual project capacity before absences. It then applies the absence percentage to that total. The resulting lost hours are subtracted from planned capacity to estimate available project time. Lost capacity is also shown as person-days and as an average full-time-equivalent (FTE) amount.

How to use this calculator

  1. 1Enter the number of people working on the project.
  2. 2Add the planned working days for each person over a year.
  3. 3Enter the average project hours available on each working day.
  4. 4Enter the expected annual absence rate as a percentage.
  5. 5Review the lost project hours, remaining capacity, and equivalent capacity loss.

Example Calculation

Team size

10

Working days per employee per year

220

Project hours per working day

7.5

Annual absence rate

5%

Project time lost to absence

825 hours per year

The team has 16,500 planned project hours annually. At a 5% absence rate, about 825 hours, or 110 person-days, are lost, leaving approximately 15,675 available project hours.

Frequently asked questions

What is an annual absence rate?

An annual absence rate is the percentage of planned working time expected to be lost through sickness, unplanned leave, and other absences during a year.

How are project hours lost to absence calculated?

Planned annual project hours are multiplied by the absence rate. For example, 10,000 planned hours at a 5% absence rate produces an estimate of 500 lost hours.

Should annual leave be included in the absence rate?

Usually no. Enter working days after planned annual leave and public holidays have been removed, then use the absence rate for unplanned or separately tracked absences.

What does FTE capacity lost mean?

FTE capacity lost expresses the absence allowance as an average full-time-equivalent share of the team. A 5% absence rate in a 10-person team is equivalent to 0.5 FTE of annual capacity.

Can this calculator help with project staffing plans?

Yes. It can help you allow for likely unavailable time when estimating delivery capacity, scheduling work, or considering contingency staffing.

Why might actual available project time differ from the estimate?

Actual capacity can change with seasonal absence patterns, staff turnover, training, meetings, workload changes, overtime, temporary cover, and the timing of absences.

Explore Related Calculators

Absence Rates Project Budget CalculatorEstimate how employee absence rates and replacement costs can increase a project's planned budget.Calculate →Absence Rates Project Budget (Individual) CalculatorEstimate how one employee's absence rate could affect project staffing costs, replacement costs and the available project budget.Calculate →Absence Rates Project Budget (Team) CalculatorEstimate the staffing budget, productive capacity and absence cover allowance for a project team using expected absence rates.Calculate →Absence Rates Project Budget (Annual) CalculatorEstimate the annual budget impact of employee absence using headcount, salary, absence rate, employment costs and replacement cover.Calculate →

Assumptions and warnings

Assumptions

  • The absence rate applies evenly across the team and throughout the year.
  • Working days entered are planned working days before absence is deducted.
  • Each working day is assumed to contain the same number of productive project hours.
  • The estimate does not account for overtime, temporary cover, changing workloads, or differences between individual absence patterns.
  • Results are planning estimates rather than a forecast of actual attendance.

Warnings

  • Actual absence levels can vary substantially by role, season, workplace policy, and individual circumstances.
  • Use this estimate alongside current attendance data and project-specific staffing plans.
Absence Rates Project Time (Annual) Calculator