The Complete Guide to Shrinkage Calculation
Master the two components of shrinkage and learn how to calculate, track, and strategically reduce it.
What is Shrinkage?
Shrinkage is the percentage of paid working time during which agents are unavailable to handle contacts. It is one of the most critical inputs in WFM — getting it wrong leads to systematic understaffing or overstaffing, regardless of how accurate your forecast is.
The core formula:
Internal vs External Shrinkage
Shrinkage is split into two categories — understanding this distinction is essential for root cause analysis and reduction strategies.
Internal Shrinkage (On-site, planned)
These are activities that happen at the workplace and are largely within the control of the WFM or operations team:
- Scheduled breaks — morning tea, lunch, afternoon breaks
- Team meetings and huddles
- Training and coaching sessions
- After-call work (ACW) — if treated as offline time rather than part of AHT
- System downtime / log-in issues
- Outbound callbacks or admin tasks
External Shrinkage (Out-of-office, harder to control)
These activities remove agents from the schedule entirely:
- Planned annual leave / vacation
- Sick leave / unplanned absence
- Public holidays
- Maternity / paternity leave
- No-shows
- Lateness and early departures
Calculating Shrinkage: Step by Step
Method 1: Interval-level (for scheduling)
Method 2: Weekly/Monthly (for capacity planning)
Gross Headcount Formula
Once you have shrinkage, apply it to convert net staffing requirement (from Erlang C) to gross scheduled headcount:
| Net HC | Shrinkage | Gross HC Needed |
|---|---|---|
| 20 | 20% | 25 |
| 20 | 25% | 26.7 → 27 |
| 20 | 30% | 28.6 → 29 |
| 20 | 35% | 30.8 → 31 |
Industry Benchmarks
| Component | Typical Range | Notes |
|---|---|---|
| Breaks & Lunch | 8–12% | Regulated by employment law in most countries |
| Training & Coaching | 3–6% | Higher in high-attrition or product-change environments |
| Meetings & Admin | 2–4% | Often underestimated |
| Annual Leave | 4–6% | Varies by country (EU higher than US) |
| Sick Leave | 2–5% | Seasonal spikes in winter |
| No-shows / Late | 1–3% | Highly correlated with engagement scores |
| Total Shrinkage | 20–35% | 25% is a common industry target |
Reducing Shrinkage Without Harming Agents
- Stagger breaks: Spread breaks across intervals rather than clustering at the top of the hour. Even a 10-minute shift in break times can improve coverage by 5%.
- Schedule training in troughs: Use forecast troughs (low-volume periods) for training and meetings rather than peak hours.
- Reduce avoidable sick leave: Track patterns — Monday/Friday sick leave spikes often signal engagement issues, not illness. Coaching and flexible scheduling can help.
- Automate ACW: Reducing average after-call work (e.g., through CRM automation) reduces the internal shrinkage component if ACW is tracked separately from AHT.
- Review leave management: Implement leave request systems with auto-approval rules based on coverage thresholds — this improves leave predictability.