Minimum staffing calculator for 24/7 cover
A 24/7 line has a staffing floor that has nothing to do with volume: someone has to be there, usually two people, every hour of the week. Enter the hours covered, the minimum on at any time, contracted hours and shrinkage, and the calculator gives the FTE floor and the hours it consumes. Volume then adds to it, it does not replace it.
Before any contact volume.
- Theoretical minimum
- 12.8
- Agent-hours to cover per week
- 336.0 h
- People, if all full-time
- 15
If shifts tiled the week exactly.
Show the working
- Cover to provide = 168 h × 2 agents = 336 agent-hours a week.
- An FTE delivers 37.5 × (1 − 30%) = 26.3 productive hours a week, so the floor is 336 ÷ 26.3 = 12.8 FTE.
- At 90% roster efficiency, 12.8 ÷ 0.90 = 14.2 FTE to roster.
Doing this for every interval of the week? Pebble WFM computes the requirement from your forecast and builds the roster. Free month, no card needed.
How the minimum staffing floor is calculated
Multiply the hours you cover by the minimum agents present and you have the agent-hours a week that exist regardless of volume. For 24/7 with two agents that is 336 hours, the same every week of the year.
Divide by the productive hours an FTE actually delivers, contracted hours less shrinkage, and you have the theoretical minimum. Divide again by roster efficiency, because a week of 168 hours does not tile neatly into shifts, and you have the number to roster: usually thirteen to fifteen FTE for two people around the clock.
Volume is then layered on top for the hours when it exceeds what the floor can handle, using the week planner. Overnight the floor usually exceeds the volume requirement, which is why overnight cover is expensive per contact and why it is often the first thing outsourced or automated.
Frequently asked questions
- Why two agents and not one?
- One agent cannot take a break, cannot be on a call when the next one arrives, and cannot be sick. Two is the smallest number that keeps the line open without every absence being a closure, and it still leaves the second contact waiting.
- Why is the floor so high for so few people?
- Because 168 hours is 4.5 full-time weeks, and shrinkage means each FTE only delivers about 26 productive hours of them. Two seats around the clock is fourteen salaries. This is the arithmetic behind follow-the-sun arrangements and overnight outsourcing.
- Does this replace the Erlang calculation?
- No. It is the floor; Erlang gives the requirement for each interval; the roster needs the larger of the two in every interval. During the day the Erlang number wins; at 3 a.m. the floor does.
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