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Reply To: Using Excel to Calc Forecasted SLA

Tom Howard

Hi Jamie, Magnus is right that the SLA is extremely high with your example – pretty much perfect performance. That’s no surprise because you have 149 staff ready to answer only 1076 (fairly short) calls in an hour. To answer your more general question, our company offers an Excel add-in for call center analysis called CC-Excel. This adds several functions to Excel that you can use to estimate call center performance.

I’ve highlighted CC-Excel‘s SLA formulae below, in red:


Function name Description
CCXLAgents() Estimates the number of agents you need to handle incoming calls within specified service level parameters.
CCXLCalls() Estimates the number of calls that your inbound call center can handle within specified service level targets.
CCXLDuration() Estimates the average length call that your call center can handle.
CCXLASA() Estimates the average speed in which your center’s calls will be answered.
CCXLQueue() Estimates the average number of your inbound calls that will be queued and waiting for presentation to an agent.
CCXLOccupancy() Estimates the percentage of their time that your call center’s agents will be busy handling inbound calls.
CCXLAllBusy() Estimates the percentage of calls that will arrive while all your agents are occupied, and will therefore enter a queue.
CCXLService() Estimates the percentage of calls that will be answered within a specified service time.
CCXLLines() Estimates the number of telephone lines that are required to handle the inbound calls into your call center.

CC-Excel’s strength is the flexibility and freedom it gives you to design workbooks that meet your exact requirements, rather than being tied to the formats and assumptions of Windows workforce management applications. With some knowledge of Excel, you can use its more advanced features such as lookup tables, conditional formatting and charting to build complex modelling tools.


All the best,
Tom Howard,
Westbay Engineers Ltd.