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Calculate the theoretical minimum workforce for continuous coverage, understand why real operations need relief capacity, and test the result against actual roster constraints.
One continuously staffed position requires 168 staffed hours per week. If each employee contributes 40 hours, the theoretical requirement is 4.2 FTE, which means at least five whole employees before leave, sickness, training, qualifications, availability and rest rules are considered.
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Multiply the number of positions that must be covered at the same time by the hours of coverage per day and days per week. Divide the result by the usable weekly hours available from one employee.
The raw FTE calculation assumes every worker is interchangeable and available for all of their planned hours. Real workforces are not. Annual leave, sickness, training, part-time contracts, qualifications, night availability and recovery rules all reduce usable capacity.
That is why a staffing estimate should be treated as capacity planning, not proof that a valid roster exists.
A site may only need two people on duty at once, yet require a much larger pool to sustain those two positions across every day and night of the week. Peak concurrent headcount describes the immediate requirement; total workforce capacity describes what is needed to rotate people through that requirement over time.
Scheduling patterns and staffing formulas are planning aids. Whether the schedule works depends on the workers, roles, qualifications, availability, leave, rest rules and other requirements that apply to your organisation.
The raw calculation is 168 divided by 40, or 4.2 FTE. Because you cannot roster 0.2 of a person, that means at least five whole employees before accounting for relief and other constraints.
It is the mathematical minimum only. In practice, leave, sickness, training, unavailable time, role requirements and work rules generally mean you need more usable capacity.
Two simultaneous positions require 336 staffed hours per week. Divide 336 by the usable weekly hours per employee, then account for leave, availability, qualifications, rest and other working limits.
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