The AGENTSB function calculates the number of servers required to answer a specified percentage of calls (or SLA) within a busy period.

You can use the AGENTSB function with other functions such as AGENTS, ERLANGB, and ERLANGC to account for a range of resource management situations.

AGENTSB(SLA, Arrival rate, Average duration)

ArgumentData typeDescription
SLANumberThe percentage of requests that need to be processed within the Target response time.
Arrival rateNumberThe interval between the arrival of each request.
Average durationNumberThe average duration it takes to process each request.

The AGENTSB function returns a number, which is the number of agents required to prevent any requests being placed on hold.

The Arrival rate and Average duration arguments do not have to use a specific time unit. For example, they can be seconds or minutes. However, both arguments must use the same time unit.

Call center planning functions are unavailable in Polaris. Learn more about the differences between Anaplan calculation engines.

In this example, the Call Centers list is on columns, and line items on rows. The three line items contain the data for the AGENTSB function for each call center:

  • The percentage of calls that must be responded to within the target response time, or SLA (uses the percentage number Format)
  • The interval between each request arriving
  • The average duration it takes to complete requests

The Servers to meet SLA line item uses the AGENTS function to calculate how many agents are needed to answer the percentage of calls specified in the SLA.


Call Center 1Call Center 2Call Center 3Call Center 4
Service Level Agreement85%87%92%85%
Request Arrival Rate0.76840.93581.4261.219
Average Duration18.6723.2524.8717.39

Servers to meet SLA

AGENTSB(Service Level Agreement, Request Arrival Rate, Average Duration)

16233922