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WFM Clubs — Erlang C Staffing Calculator
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Colour coding:
Blue = Input (change these)
Black = Formula (auto-calculated)
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INPUTS — Enter your interval data below
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Call Volume (calls per interval)180Number of calls arriving in the interval
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Average Handling Time — AHT (seconds)270Talk time + After-Call Work
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Interval Length (minutes)3030 or 15 minutes
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Target Service Level (%)80.0%e.g. 80% answered within target time
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Target Answer Time (seconds)20e.g. 20 seconds for 80/20
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Shrinkage (%)25.0%Total shrinkage for gross HC
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INTERMEDIATE CALCULATIONS
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Traffic Intensity — A (Erlangs)27.00
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Minimum Agents (must exceed A)27
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RESULTS
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Net Agents Required32
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Erlang C — Probability of Waiting0.264
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Achieved Service Level81.7%
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Occupancy %84.4%
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Average Speed of Answer — ASA (seconds)14.3
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Gross HC Required (inc. shrinkage)43
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Net Agents Required = minimum agents in READY state to achieve Target SL via Erlang C.
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Gross HC adds shrinkage (breaks, training, leave). Schedule this number of agents.
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Blue cells are inputs. The Staffing Table sheet shows all N scenarios — do not edit it.
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