Contact Centers: How to Calculate Staff Levels and Scheduling Requirements

In calculating contact center staffing requirements, adjustments must be made to factor in all the activities and situations that make staff unproductive. This unproductive time, called staff shrinkage, is defined as any time for which staff members are paid but not available to handle calls. Such activities might include breaks, meetings, training sessions or off-phone work.

In most centers, staff shrinkage ranges from 20 percent to 35 percent. You can account for this shrinkage factor by dividing the staff requirement by the productive staff percentage (or 1 minus the shrinkage percentage). For example, if 24 staff hours need to be filled and your shrinkage factor is 30 percent, then 24/0.70 yields a requirement of 34 staff members.

Agent Group Size
Not surprisingly, the size of your contact center, known as agent group size, has a major impact on staffing levels within your contact center. Centers handling larger volumes of calls naturally will be more efficient than smaller groups. This is due to the economies of scale of large groups.

But if your call volume doubles, you don’t necessarily require twice the number of staff to meet your service goals. And when call volume increases eightfold, only about six times the number of staff is needed. As staff volume grows, the staff to workload ratio gets smaller and smaller.

The reason for these increased efficiencies and the lower staff-to-workload ratio is simply that with a higher volume of calls, there’s a greater likelihood that when an agent is finished with a call, there’ll be another call coming in right behind it for that person to handle. With a bigger volume, each person has the opportunity to process more calls each hour and spends less time in an available state waiting on a call to arrive. As a result, you don’t need as many staffers.

Staff Occupancy
So if a higher volume of calls means that your reps are busier, then you might assume that bigger is always better, right? After all, these folks are being paid to handle calls, so don’t we want them busy all the time doing just that? The answer is yes and no: Although you want your staff to be busy processing lots of calls, having them too busy (in other words, no available time or “breather room” between calls) isn’t such a good idea either.

The measure of how busy agents are is called “agent occupancy.” It’s the percentage of logged-in time that an agent actually is busy in talk or wrap-up time. It’s calculated by dividing the amount of workload by the staff hours in place. Say you have 12 staffers handling 8.3 hours of workload. At one staff hour per agent, agent occupancy is just 69 percent. If your call volume is doubled and you have 21 staffers in place, twice the workload is being handled without doubling the workforce, so each person is busier. In this case, occupancy increases to 79 percent.

As call volume grows, increased efficiencies and economies of scale come into effect — occupancy goes higher and higher. And while we want our staff to be productive and busy, asking staffers to stay occupied at a 94 percent rate isn’t realistic.

Most call centers aim for the 85 percent to 90 percent range because occupancy rates higher than that lead to all kinds of undesirable call-handling behaviors as well as a high turnover rate.

Penny Reynolds is a founding partner of The Call Center School, a company that provides a wide range of educational offerings for call center professionals. She can be reached at (615) 812-8410 or via e-mail: penny.reynolds@thecallcenterschool.com.