The ErlangC equation is a standard tool in inbound contact centres for estimating the number of advisors needed to meet a service level target, typically defined as answering a set percentage of calls within a specific number of seconds. It works best in environments where every advisor can handle every call, and is usually applied to each 15- or 30-minute interval. The formula originates from queueing theory, a branch of Operational Research.
Erlang C is not recommended for centres with complex multiskilling, or where advisors handle a blend of inbound calls and other tasks such as outbound calls or email. In these cases, other modelling approaches will produce more accurate results. We can help you select and implement the most suitable resourcing method for your operation to ensure the best match between workload and staffing.
You can try our ErlangC Calculator using the link below. It will estimate the number of inbound call centre advisors needed to achieve your service goal. Please note: the result does not include allowances for absences such as meetings, sickness, or holidays. You should therefore schedule extra advisors to make sure the required number are actually available at the right times.
