Span of Control Calculator NZ 2026
This calculator works out how many people you actually need to cover your opening hours, which is reliably more than the roster suggests. You enter how many hours a week you are open, how many staff have to be on at once, the contracted hours of one person, an allowance for leave and absence, and how many staff one supervisor can reasonably carry. It returns the staff hours you need each week, the full time equivalent that represents, the headcount to hire and the number of supervisors that headcount requires. The allowance is the number that decides whether a roster works. Four weeks of annual holidays, twelve public holidays and ten days of sick leave together take roughly fifteen percent of a full time year off the roster before anything unusual happens at all, so a team sized exactly to the shifts has nobody spare the first time someone takes leave or calls in sick, and the gap gets filled with overtime at a premium or with a manager working the floor. On the supervisor side there is no correct ratio. Repetitive, well defined work with experienced staff sits comfortably at one to ten or more; complex work, safety critical tasks, high turnover or a lot of new starters pull it down sharply. Use your own experience rather than a benchmark, and treat a ratio that keeps generating overtime as evidence it is set too high. It is built for anyone rostering a shop, cafe, bar, clinic or depot.
Headcount is rounded up, because you cannot roster a fraction of a person. The allowance covers annual holidays, public holidays and sick leave, which together take roughly 15 percent of a full time year off the roster before anything unusual happens.
How it works
Base staff hours are your opening hours multiplied by the number of people who must be on at once. The leave and absence allowance is added to that, because those hours still have to be covered by somebody when the rostered person is away. Full time equivalent divides the result by the contracted hours of one person, and headcount rounds that up, since a roster cannot use a fraction of a person. Supervisors divide the headcount by your staff per supervisor ratio and round up as well. The weekly wage cost prices the staff hours you actually need, including the allowance, at your average hourly rate, so it reflects the cost of a roster that can absorb leave rather than one that only works when everybody turns up.
Worked example
A business is open twelve hours a day, seven days a week, which is 84 hours, and needs two people on at all times. That is 168 staff hours a week before any allowance. Adding 15 percent for annual holidays, public holidays and sick leave takes it to about 193 hours. With staff contracted to 32 hours each that is 6.04 full time equivalent, so seven people are needed once the number is rounded up to whole humans. At one supervisor per eight staff, one supervisor covers it. At an average $26.00 an hour the 193 covered hours cost about $5,023 a week in wages. Sizing the team to 168 hours instead would look cheaper and would break the first week somebody took leave.
Related calculators
- Roster Cost: what the resulting roster costs to run.
- FTE: headcount to full time equivalent.
- Headcount Budget: the cost of hiring to this number.
- Workplace Incident Cost: what an injury does to your cover.
- Overtime or a New Hire: covering the gap the other way.
- NZ Property Rates & Insurance Affordability Calculator: Council rates by region, home and contents insurance and the EQC levy, added into the yearly cost of owning.