Using an Erlang ‘C’ Calculator in the Call Center
This post was originally published on CX Master but it has been updated with additional information.
Erlang ‘C’ is a Nobel winning formula used in the Call Centre and Operations industries to determine the correct and appropriate level of staffing based on key call metrics. The scary looking formula for this is below and the even scarier explanation from Wikipedia is here.
From a Call Centre and Staffing Point of view, the primary elements considered are as follows:
- Average Talk Time
- Calls/per specified period (15min is a good benchmark)
- Specified Service Metrics or SLA (ie. 80/20 <- 80% of calls answered in 20s or less etc…) … correspondingly, you want to consider your abandon %’age here also. Are you willing to accept that some of your customers will hang up? If so, how many & consider what impact that will have on your business in the long run!
With this information in hand and using the formula, you are able to determine how many resources you need in a given period to meet your customer demand. Using some free online tools (links provided below), you are also able to determine your required resources based on a specified timetable and rotation. For example, if the formula states you need 8 resources between 8am-9am and you are running a 24/7 call center the actual number of staff you need to employ is ‘X’.
Some Good Free Erlang ‘C’ Calculators –
- Online Traffic Calculators
- Erlang ‘C’ Calculator
- This last one is a downloadable application & HIGHLY RECOMMENDED
With this in mind, you still need to plan for excess capacity relevant to staff absenteeism either planned or unplanned. So although the formula only called for 8 staff & your overage based on a 24/7 call centre is ‘X’ … you should actually plan to have ‘Y’ resources available to cover these gaps!!
Why Does it Matter?
Using a calculator like Erlang ‘C’ can make a dramatic difference to how you schedule your teams. While many managers use it to demonstrate the lack of resources to the SLT (let’s be honest – we’ve all been there), in some cases it helps demonstrate how you can restructure your teams to better provide support without adding any additional heads.
In one of the jobs I was in, that’s actually exactly what happened. We had multiple queues for products and services and after going through this exercise we were able to transition how we’d staffed two of the queues to improve services for our customers without increasing the size of the team at all.
Now I’ve told you how it works, but not really why it matters. Well, simply put if you cannot answer your customers in a timely manner you are not providing them with the service they’ve paid for and that they deserve. If you want to succeed in today’s economy, service is something that needs to be considered near the top of any list.