Online Erlang Calculator - for Call Centre Staffing (Version 3.2)

Can now calculate up to 10,000 agents!

Call Centre Erlang Calculator
Calculate the number of staff required to reach an agreed service level
Incoming Calls
in a period of
Average Handling Time (AHT)
Required Service Level
% Answered in
Target Answer Time
Advanced Options
Max Occupancy (What's this?)
% Percent
Shrinkage (What's this?)
% Percent

How To Use This Calculator

  1. If you have 200 calls per hour, then enter the number of incoming calls as 200 and the period is 60 minutes.
  2. The Average Handling Time is the amount of time that a person (an agent) takes to handle a phone calls. This includes the talk time as well any paperwork time (wrap-up time) before they are able to answer the next call. This should be in seconds.
  3. Put in your Service Level target and time. So if you wanted to handle 90% of calls in 15 seconds, put in 90 and 15. If you are uncertain of this the industry "average" is 80% of calls answered in 20 seconds.
  4. This contact centre staffing calculator is based on the Erlang C formula which was invented by the Danish Mathematician A.K. Erlang.
  5. We also have a more flexible Microsoft Excel based version of this calculator. You can download the free Excel Erlang Calculator
  6. This calculator works on probabilities, so may appear to overstate the number of agents needed at low levels. So for example if you enter 0 calls per hour it will say that you need 1 agent. This is quite correct, as there may be a possibility that one call may come in. In practicality, you may decide to not schedule any staff.
  7. The maxium number of agents that the calculator can calculate before shrinkage is applied is 10,000 Agents.
  8. Shrinkage is a factor designed to take into account holidays, sickness etc. For more information Read this article on how to calculate shrinkage

Need To Include Webchat And Emails?

Need a Multi-Channel calculator? Then use our free Multi Channel Calculator

Terms and Conditions

Use of the ERlang Calculator is subject to our standard terms and conditions.