Before you make a calculation, you should select the traffic unit you wish to use. You may work in either Erlangs or C.C.S.
You can use the Erlang B Calculator to find any one variable if you know the other two. The calculator is split into three entry areas, each representing a variable (Busy hour traffic, blocking and lines). Each area has a radio button and an edit box. Click on the radio button which represents the quantity which you wish to calculate. Enter the two figures which you know into the edit boxes provided from them.
When entering figures into the edit boxes, a full stop or period should be used as a decimal mark, NOT a comma as is the convention in some European countries.
To start the calculation, press the Calculate button. After a short time, the unknown figure will be displayed in the relevant edit box. If you want to stop a calculation before it has been completed, press the Stop button.