Erlang C

Definition of Erlang C

Erlang C is a mathematical formula used in call center and telecommunication industries, specifically for calculating the required number of agents to handle incoming calls or requests. The formula takes into account the arrival rate of calls, the average handling time, and the desired level of service. Erlang C aims to optimize staffing levels to minimize both customer wait times and operational costs.


The phonetics of the keyword “Erlang C” are:ɛərˈlæŋ siː

Key Takeaways

  1. Erlang C is a telecommunication formula used for calculating the number of agents required in a call center to maintain optimal service levels.
  2. It considers factors such as call arrival rate, average handling time, and target service level to determine the staffing needs in a call center.
  3. Applying Erlang C helps in reducing customer waiting time, improving agent utilization and overall efficiency of the call center operations.

Importance of Erlang C

Erlang C is a significant technology term as it plays a crucial role in the domain of telecommunications and call center operations.

It is a mathematical model developed by A.K.

Erlang, which enables businesses to determine the number of call center agents needed to meet specific performance parameters such as service level and response time.

By efficiently predicting the necessary staffing levels and balancing resources, it ensures optimal customer experience and service quality while reducing operational costs.

Erlang C is widely used by contact centers around the world, making it an indispensable tool for effective workforce planning and management in many industries.


Erlang C is a widely used mathematical model in the field of telecommunications, particularly in predicting call center performance and resource planning. Developed by A.K.

Erlang in 1917, the primary purpose of this model is to estimate the appropriate number of call agents needed to maintain a certain level of service quality, in terms of both wait times and call handling efficiency. The model takes into account factors such as the average arrival rate of calls, average call handling time, and the number of available agents, enabling organizations to optimize their staffing levels and overall operational costs.

Call centers, in particular, rely heavily on Erlang C to make informed decisions when it comes to forecasting workforce requirements and setting service level targets. By leveraging this powerful mathematical tool, managers can create optimal balance between staffing costs and customer satisfaction, ensuring that customers receive the desired support while keeping operational expenses in check.

Moreover, Erlang C can also be utilized in small and large-scale contact centers, across various industries, making it a versatile and indispensable tool for service-based organizations seeking efficiency and excellence in their customer support operations.

Examples of Erlang C

Erlang C is a mathematical model used in the field of telecommunications, specifically call center management, to predict call handling capacity and estimate staffing requirements. Here are three real-world examples of its application:

Call Centers: Erlang C is widely used in call centers to calculate the required number of agents to handle incoming calls efficiently. By applying the Erlang C formula, call center managers can determine the optimal staffing levels to maintain target service levels and reduce the wait time for customers. This leads to improved customer satisfaction and cost efficiency.

Emergency Response Services:Emergency response services particularly use the Erlang C model to estimate staffing levels for call operators responding to emergency calls, like 911 in the United States. Erlang C helps maintain target service levels by ensuring there are sufficient operators available to handle incoming calls, minimizing the risk of callers being put on hold during critical situations.

Helpdesk and Technical Support:Companies that provide IT support and helpdesk services utilize Erlang C to forecast the number of agents needed to manage support ticket queues effectively. This enables businesses to avoid overstaffing or understaffing their helpdesk teams, and to deliver timely assistance to customers facing technical issues.In summary, Erlang C is an essential tool in the telecommunications industry for managing staffing requirements and maintaining service levels in call center environments, from customer support to emergency response.

FAQ: Erlang C

What is Erlang C?

Erlang C is a mathematical model used in call center environments to predict queue waiting times, agent staffing, service level, and other performance-related metrics. It is widely applied to manage resources effectively and optimize the overall efficiency of call center operations. The model was developed by A.K. Erlang, a Danish mathematician, as an extension of the Erlang B model.

What are the key components of Erlang C?

There are three main components of the Erlang C model: offered load (measured in Erlangs), number of agents, and probability of delay. Offered load is the total traffic volume that is presented to a call center, measured in Erlangs – a unit representing the ratio of active call time to total time available. The number of agents refers to the total number of customer service representatives working in the call center. Finally, the probability of delay represents the likelihood of a customer being placed on hold or in a queue when they call the call center.

How is Erlang C used in call center management?

Erlang C is widely used by call center management to estimate optimal staffing levels, minimize wait times, and maximize service levels. By analyzing historical data, managers can utilize Erlang C calculations to forecast both the number of agents required during peak hours and the percentage of calls that will be answered within a specified time-frame. This information helps organizations make informed decisions when allocating resources and scheduling staff, ultimately improving customer satisfaction and overall efficiency.

What are the limitations of Erlang C?

While Erlang C is an essential tool in call center management, it has its limitations. The model assumes that incoming call volume and call handling times are consistent and stable. It does not consider factors such as call abandonments, multi-skilled agents, or agent utilization. In addition, it is not designed to handle other channels of communication such as email, live chat, and social media. Consequently, modern call centers and contact centers often use other advanced workforce management tools to complement the Erlang C model.

How do I calculate Erlang C?

To calculate Erlang C, you’ll need three pieces of information: offered load, number of agents, and probability of delay. While the formula itself is complex, several Erlang C calculators are available online to assist in performing these calculations. By inputting your call center’s offered load and desired service level, you can use an Erlang C calculator to determine the optimal number of agents needed to achieve your service goals.

Related Technology Terms

  • Queueing Theory
  • Call Center Forecasting
  • Customer Service Level
  • Telecommunications Traffic Modeling
  • Probability of Waiting in a System

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