How to calculate call centre staffing in 2023 (incl. free Excel scheduling template)

Free call centre scheduling template
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Picture of Natasha Ratanshi-Stein

Natasha Ratanshi-Stein , Founder & CEO

Efficient resource allocation is crucial for businesses to meet customer demands and ensure optimal performance. Determining staffing requirements and analysing call traffic is necessary when managing call centres or telecommunication systems.

While calculating call centre staffing may seem daunting, technology has undoubtedly made it easier. From using spreadsheets to online Erlang C calculators, call centres use various methods to calculate staffing needs. 

But what about using an Erlang calculator in Excel? Scroll ahead to learn how you can use Excel as a staffing calculator. 

Plus we’ve included a call centre staffing model Excel template to make things easier for your CX team. We don’t think spreadsheets are fit for purpose for scaling teams, but if you’re going to use one we want to help you do it right. 

Erlang calculator for call centre staffing

Erlang calculators are widely used in call centre staffing to help determine the appropriate number of surfers needed to handle incoming calls based on expected call volumes and desired service levels. The concept of Erlang, named after the Danish mathematician A.K. Erlang, is a mathematical formula used to analyse and predict telecommunications traffic.

The Erlang calculator calculates the number of surfers required to handle a given call volume or the call volume that a given number of surfers can handle. It is calculated by considering multiple factors, like average call duration and the number of calls per hour.

The output can vary depending on different time intervals and shifts throughout the day. This information helps call centre managers allocate appropriate staffing resources to ensure optimal service levels.

Erlang calculators are valuable tools that enable call centre managers to 

  • manage their resources efficiently, 
  • minimise customer wait times, and 
  • maximise surfers’ productivity. 

By accurately predicting staffing requirements, call centres can provide better customer service, reduce customer abandonment rates, and optimise operational costs by avoiding overstaffing or understaffing situations.

Get our Excel Erlang calculator to calculate staffing requirements.

Excel Erlang calculator vs. online Erlang calculators

Want to know the difference between using an Online Erlang calculator and an Excel Erlang calculator? Here’s a quick distinction between them:

Erlang calculator Excel Online Erlang calculator
An Excel Erlang calculator is a spreadsheet-based tool. Online Erlang calculators are web-based tools accessible through internet browsers.
Offers flexibility and customisation options within the spreadsheet. Offers convenience and real-time calculations.
You use formulas and macros to calculate staffing requirements and other call centre metrics. You can directly input the numbers to calculate call centre staffing.
There’s no requirement for a strong internet connection. You need a strong internet connection to access the calculators online.
Best suited for small teams and limited calculations. Works well for small and large teams requiring collaboration and instant accessibility.

Pros and cons of an Excel Erlang C calculator

Now that you know the functionality and capability of using an Excel Erlang C calculator , here are the pros and cons you must consider ⬇️

Pros of using an Excel Erlang C Calculator

Familiarity: Excel is a widely used spreadsheet program, and several organisations are already familiar with its interface and functionality. An Excel Erlang C calculator allows users to leverage their existing Excel skills and work in a familiar environment.

Flexibility: Excel provides greater flexibility when it comes to customisation. Users can tailor the Erlang C calculator to their needs by modifying formulas, inserting additional calculations, or integrating it with other Excel functionalities.

Ease of use: Excel Erlang C calculators are user-friendly, with inputs and outputs organised clearly and intuitively. Users can enter relevant data, such as call arrival rate, average call duration, and the number of surfers, to obtain the desired results quickly.

Analysis and visualisation: Excel offers various tools for data analysis and visualisation. With an Erlang C calculator in Excel, users can calculate critical metrics and generate charts, graphs, and reports to understand better and communicate the results.

Accessibility: Excel is widely available and accessible across different devices and platforms. With Excel apps, users can use Excel Erlang C calculators on their desktop computers, laptops, and other mobile devices.

Download free Excel template

Cons of using Excel Erlang C Calculator

Potential for errors: Like any manual calculation, using an Excel Erlang C calculator has the possibility of human errors. Users may inadvertently input incorrect data, use inaccurate formulas, or make other mistakes that can impact the accuracy of the results.

Limited scalability: Excel has limitations in handling large datasets and complex calculations. As the number of inputs and calculations increase, Excel’s performance may degrade, leading to slower calculations or system crashes. This can be a constraint when dealing with high call volumes or complex Erlang C models.

Version compatibility: Different versions of Excel may have slight differences in functionality, formula syntax, or features. This can result in compatibility issues when sharing or transferring Excel Erlang C calculators between users or systems using different Excel versions.

Lack of real-time updates: Excel is primarily designed for manual data entry and calculation. As a result, an Excel Erlang C calculator may not provide real-time updates or dynamic adjustments based on changing conditions, such as call volumes or surfer availability. Users may need to update the inputs and recalculate the results manually.

Limited collaboration features: While Excel does offer collaboration features, such as sharing and tracking changes, it may not be as efficient as dedicated collaboration tools or cloud-based platforms. Collaborating on an Excel Erlang C calculator may involve emailing or sharing files, leading to version control issues and difficulties in simultaneous collaboration.

Note: Dedicated Erlang C calculators and software solutions are specifically designed for call centre operations and offer more advanced features and capabilities than an Excel-based calculator.

If you run a large support team or call centre, look for team planning software that offers automated call centre forecasting instead of relying on online calculators. 

Wrapping up

Having reliable and efficient staffing calculations is crucial to adapt to the changing customer demands. 

The Excel Erlang Calculator remains a valuable resource for call centre professionals, enabling them to navigate the complexities of workforce management and deliver superior customer experiences.

Download the free Excel template

If you’re looking for a solution to manage your forecasts, shifts, and schedule without an endless stack of paperwork – your search ends with Surfboard.

Book a demo to learn how we can help you improve workforce management for your call centre. 


How should one calculate average call time in Excel?

To calculate the average handling time of a call centre employee, sum up the total talk time, total hold time, and total after-call task time. Next, you have to divide it by the number of calls. Use the AVERAGE function to calculate the average time. Before applying the formula, change the cell format to the Time format like this👇

  • Right-click in the cell where we want to insert the AVERAGE time formula.
  • Choose Format Cells, and in the Number tab, choose the “time format.”
  • Select OK to set it in time format.

What is the ratio for call centre staffing?

The ratio between the number of surfers available to handle incoming calls and the anticipated call volume in call centre staffing ranges between 8:1 and 15:1. 

Why should one choose the Surfboard Excel template for call centre staffing calculation?

Surfboard’s free call centre staffing Excel template includes all the metrics call centres need to accurately calculate the number of surfers required during a particular period. It also has the formula embedded within the template, so you wouldn’t have to add the numbers manually. 

What is the formula for call centre staffing?

The formula to calculate call centre staffing is the Erlang C formula, which is commonly used in call centre management. The formula is as follows:

S = (A * T) / (C * (1 – P))


S = Number of surfers required.

A = Average number of calls arriving per unit of time (call arrival rate).

T = Average time per call (call duration).

C = Desired service level target (as a decimal).

P = Probability that a customer waits (calculated using the Erlang C formula).