Erlang for Excel FAQ

Here is a list of questions we are commonly asked about Erlang for Excel. Please contact us if you have any others.

How can I calculate Erlang B in Excel worksheets?

Erlang for Excel adds eight Erlang traffic functions to Microsoft Excel that help you model telecommunications systems in your own workbooks. They work exactly the same as Microsoft Excel’s own built-in functions: in a blank cell, you enter an equals sign (=) followed by the function’s name and its arguments.

For example, a cell with this function:


will display the result 117, which is an estimate of the number of lines required to handle an offered busy hour traffic of 100 Erlangs with a blocking factor of 0.01 (1%). Instead of entering numbers as the arguments, you could specify references to other cells within the workbook.

What is an Erlang?

An Erlang is a unit of traffic measurement. In practice, it is used to represent one hour of traffic although, strictly speaking, Erlangs are dimensionless.

Does Erlang for Excel include examples?

Erlang for Excel is installed with an example workbook that includes ten calculators demonstrating the functions’ use.

Erlang for Excel calculators

How accurate are Erlang for Excel’s results?

Erlang for Excel uses the Erlang traffic models that were developed in the first half of the twentieth century to model the performance of telecommunications systems. They make certain assumptions about the nature of offered traffic, which may not necessarily apply in your case. For example, they assume random (Poisson) arrivals. This is usually reasonable, but sudden peaks of calls resulting from a radio or television advertisement can give unexpected results. In these circumstances, you should use the functions with caution and common sense.

Can I share Erlang for Excel workbooks with colleagues?

The calculations behind Excel add-ins are not transportable within workbooks. Only references to the functions’ names are embedded within workbooks and the calculations themselves are resolved using coding that is integrated within an Excel installation. Anyone wishing to make use of the workbooks you create must also have Erlang for Excel installed locally on their computer.

What are Erlang for Excel’s operational limits

Erlang B functions in Erlang for Excel work up to 90,000 lines and 90,000 Erlangs busy hour traffic. The Erlang C functions work up to 300,000 calls per hour and 10,000 agents.

How does Erlang for Excel deal with 30 minute analytical intervals?

Erlang for Excel’s call center functions assume that your call volumes are based on the number of call handled during a one-hour period. In some cases, call volumes for only thirty minutes are available. Before you apply those values as an argument to an Erlang for Excel function, you should double them to convert them to hourly figures.

What versions of Excel does Erlang for Excel run on?

Our Excel add-ins work on all Windows desktop versions of Excel from 97 to 2021, both 32-bit and 64-bit, and with the Windows desktop version of Excel provided with Microsoft 365 (formerly Office 365) subscriptions. They will not work with Excel for the web (the cloud-based workbook product), or with any Apple Mac versions of Excel.

How much does Erlang for Excel cost?

Erlang for Excel costs $45 (US dollars) for an installation on a single computer. We also offer enterprise licences for multiple installations.

This is a once-only payment and includes free upgrades for the lifetime of the product.

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2 Replies to “Erlang for Excel FAQ”

  1. Does the Microsoft 365 excel require a different Westbay add-in (calculator) than Excel 2016? Or when I upgrade to 365 will my current Erlang model (Westbay Traffic Calculator) for Excel 2016 continue to work?

  2. The latest version of Erlang for Excel will work with the Windows desktop version of Excel provided with Microsoft 365 (formerly Office 365). We do not support Excel for the web (the cloud-based workbook product). If you have already purchased, then an upgrade to the latest version of free – just contact our support team.

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