Erlang C Calculator

Calculate call center staffing requirements

Erlang C Staffing Calculator

Calculate required agents based on call volume and service level targets

Call Volume (per hour)

Average Handling Time (seconds)

Target Service Level (80%)

Target Answer Time (seconds)

Shrinkage (30%)

The Erlang C formula calculates the probability that a caller will need to wait for an agent. It assumes calls arrive randomly and are handled in the order they are received.

About Erlang C

Understanding the Erlang C formula for call center staffing

The Erlang C formula is a mathematical equation used in call centers to calculate the probability that a caller will need to wait in a queue before being connected to an agent.

Key Assumptions

Calls arrive randomly according to a Poisson process
Call handling times follow an exponential distribution
Callers wait in a single queue until an agent becomes available
All agents have the same skills and can handle any call
Callers do not abandon the queue

Key Metrics

Traffic Intensity (Erlangs): The amount of traffic in the call center, calculated as (call volume × AHT) / 3600
Service Level: The percentage of calls answered within a target time
Agent Occupancy: The percentage of time agents spend handling calls
Shrinkage: The percentage of time agents are unavailable due to breaks, training, etc.

Note: The Erlang C formula tends to overestimate staffing requirements in situations with high abandonment rates or when calls are not handled in strict order of arrival.