Erlang C calculator

This is the original free online Erlang C calculator. Use it to estimate how many agents or operators you need to answer calls at your inbound call center or help desk.

Erlang C Calculator
Calls per hour
Call duration (s)
Avge. delay (s)

Excel version

Download high capacity Excel and Windows versions of this calculator with lifetime upgrades and support.

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Erlang C Calculator instructions

This Erlang C calculator estimates the number of staff you need to handle your calls at your help desk or inbound call center. You need to enter three values into the boxes:

  • Calls per hour: the number of inbound calls your call center receives during the hour in question
  • Duration: the average duration of those calls, in seconds
  • Avge delay: the average delay to all calls that you and your callers will tolerate

Press the Calculate button and the number of agents required to answer those calls will be displayed.

For example, if you receive 400 calls per hour of 180 second duration and you are prepared to tolerate a 30 second average delay to those calls, enter these numbers into the boxes and press Calculate. The result, 23 agents, will be displayed below the edit boxes indicating the number of agents that should be available to handle those calls.

Windows version

Westbay Traffic Calculators is a Windows package of four calculators including this Erlang C Calculator. We offer free upgrades and installation support for the lifetime of the product. The calculator works up to one million calls per hour.

Westbay Traffic Calculators - Erlang C
Westbay Traffic Calculators – Erlang C

Packaged with Erlang for Excel, our best-selling telecom software application comprises four Windows calculators for Erlang C and Erlang B. Use them predict the performance of your call center and work out how many lines it needs.

Free upgrades for life on a single computer for a once-only charge of just $99.