Call Center Capacity Planner

What it does

It quantifies the capacity decision for a single interval of a call queue. From the given call volume, AHT, and service-level target it first computes offered load: A = (calls/hour × AHT_sec) / 3600 (workload in Erlangs). Then it runs an Erlang-C iteration (A.K. Erlang, 1917 — M/M/c queueing model), increasing agent count c until the SL target is met and the occupancy ceiling is not breached. At each step it jointly computes wait probability P(W>0), service level SL = 1 − P(W>0)·e^{−(c−A)·T/AHT}, average speed of answer ASA, and occupancy A/c.

Erlang yields "need"; actual headcount comes from a shrinkage correction: Required FTE = Erlang_agents / (1 − shrinkage). Shrinkage is reported in two layers — planned (breaks, training, meetings) and unplanned (absenteeism) — because they are managed differently. The result is summarized as an SL Adequacy Score (0-100) weighting Service Level (30%), Occupancy (25%), ASA (15%), Abandon% (15%), shrinkage realism (10%), and forecast confidence (5%).

The key differentiator: it avoids single-metric blindness. If SL holds at 80% but occupancy is 95%, it flags critical — "holds on paper but unsustainable: abandon + burnout + quality collapse."

When to use it

For WFM questions like "how many should we hire", "can we hit 80/20 SL", "what if we cut shrinkage", "are we understaffed this interval". For sizing a new queue, auditing the SL risk of an existing interval, or stress-testing a scenario (shrinkage/volume shift). Useful for outsourcing (BPO) bid sizing and in-house operations planning.

Method / frameworks

• Erlang-C (M/M/c queueing) — backbone of inbound voice capacity.
• Erlang-A (Palm/Garnett) — abandonment extension; corrects Erlang-C overstaffing when abandon >5%.
• Shrinkage correction — planned/unplanned WFM standard; ~30-35% global average.
• Occupancy discipline — 75-85% sustainable band; >90% burnout/abandon signal.
• COPC CX Standard & ISO 18295-1 — performance frameworks managing SL, ASA, abandon%, FCR together.
• WFM forecast→schedule→adherence loop — skill focuses on the forecast→staffing leg.