Definition
Shrinkage covers every reason a paid hour does not become a contact-handling hour. Planned shrinkage is scheduled deliberately: breaks, coaching, meetings, training and project work. Unplanned shrinkage is lost without choice: sickness, absence, late logins and system downtime.
Total shrinkage is (planned hours + unplanned hours) ÷ total scheduled hours. Staff to schedule is then base requirement ÷ (1 − shrinkage), not base requirement × (1 + shrinkage). At 30% shrinkage, 100 agents on the phone requires 143 people rostered, not 130.
Most contact centres run between 25% and 35%. Anything under 20% usually means a component is missing from the calculation, most often training or unpaid break conventions.
Why it matters
- Shrinkage is the bridge between the Erlang C requirement and real headcount, so it drives the roster, the hiring plan and the budget.
- The divide-versus-multiply error is the most common single mistake in contact centre planning and understaffs by around 10% at typical shrinkage levels.
- A rising unplanned figure is an early warning of burnout, visible months before it appears in attrition data.
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