Teams & projects
Staffing calculator
Enter the weekly volume of work, the time each item takes, contracted hours per person and shrinkage, and get the headcount needed to cover the workload.
If you already know the workload in hours, enter it as tasks and set minutes per task to 60.
How the staffing requirement is calculated
Staffing starts from workload: tasks per week × minutes per task ÷ 60 gives the hours of work that must be done. Each employee's contracted hours are then reduced by shrinkage, the share of paid time when people are not available for that work: holidays, sickness, training, team meetings, coaching and admin. Productive hours per person = paid hours × (1 − shrinkage). Workload ÷ productive hours per person gives the exact full-time-equivalent (FTE) requirement, and rounding up gives the headcount.
Example: 1,200 tasks of 12 minutes each are 240 hours of work a week. A 40-hour employee with 30% shrinkage delivers 28 productive hours, so the team needs 240 ÷ 28 = 8.57 FTE, rounded up to 9 people. Nine people supply 252 productive hours, 105% of the workload, leaving 12 hours spare. With eight people coverage would be only 93%, and roughly 16 hours of work a week would go undone or into overtime.
| Shrinkage | Productive hours of a 40-h week | FTE for 240 h of work | Staff needed |
|---|---|---|---|
| 10% | 36 | 6.67 | 7 |
| 20% | 32 | 7.50 | 8 |
| 25% | 30 | 8.00 | 8 |
| 30% | 28 | 8.57 | 9 |
| 35% | 26 | 9.23 | 10 |
| 40% | 24 | 10.00 | 10 |
Getting the inputs right
Shrinkage is the input most often underestimated. Add up annual leave, public holidays, expected sickness, training days and recurring internal meetings, and express them as a share of paid hours: 25 days of leave and holidays alone are about 10% of a 250-day year. Operations teams that plan for 25–35% are not unusual once all of these are counted. Measure it from rotas and time records rather than guessing.
The minutes per task should be the average handling time including the follow-up work after each task, not only the visible part. This method also assumes the work can wait to be processed somewhere in the week. If tasks arrive in peaks and must be handled within minutes, such as phone calls with a service-level target, staff for the busiest interval instead (contact centres use the Erlang C model for this), because a weekly average will leave the peak hours understaffed. Part-time staff count as fractions: two people on 20 hours equal one 40-hour FTE.
Frequently asked questions
What is shrinkage in staffing?
Shrinkage is the percentage of paid time when staff are not available for productive work, such as leave, sickness, training, meetings and breaks beyond the planned ones. It is used to inflate the raw staff requirement.
How do I calculate how many employees I need?
Work out the weekly workload in hours, divide it by the productive hours one person delivers (paid hours × (1 − shrinkage)), and round up. 240 hours ÷ 28 productive hours = 8.57, so 9 people.
What is the difference between FTE and headcount?
FTE is the requirement in full-time equivalents and can be a fraction, such as 8.57. Headcount is the number of actual people, which may be higher if some work part time.