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Use this attrition calculator to measure how many employees left during a period, relative to the average number of employees. It’s a simple way to track retention trends and compare periods consistently.
Last updated: January 2026
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Count departures in the period (voluntary + involuntary). Track the same timeframe as start/end headcount.
Attrition rate
15.65%
Attrition = L / ((S + E) / 2) × 100%
Average headcount
115 ( (start + end) / 2 )
Employees left
18
Output
Attrition rate (%)
Key input
(Start + End) / 2
Use case
Workforce planning
Start = 120, End = 110, Left = 18
Average headcount
115
Attrition rate
15.65%
Attrition rate turns a raw count of departures into a comparable percentage. The most common approach is to divide departures by the average headcount across the period. Using an average helps avoid skew when headcount changes.
Attrition = L / ((S + E) / 2) × 100%Where L is employees who left, S is employees at the start, and E is employees at the end.
Attrition rate measures how quickly employees are leaving relative to your workforce size. It is a core HR health metric because it impacts hiring costs, productivity, morale, customer continuity, and long-term business performance.
A single percentage helps leadership compare periods, teams, and interventions. When tracked consistently, it becomes an early warning system for retention issues before they show up in revenue, quality, or delivery timelines.
Attrition Rate (%) = Employees Who Left / Average Headcount x 100
Average Headcount = (Employees at Start + Employees at End) / 2
Employees at Start (S): Team size at period start.
Employees at End (E): Team size at period close.
Employees Who Left (L): Departures during the same period.
Average Headcount: Normalizes growth/shrinkage effects.
Keep definitions stable over time (voluntary/involuntary, internal transfers, contractor inclusion) for valid trend comparisons.
Start 120, end 118, left 10. Average headcount is 119. Attrition is 10 / 119 x 100 = 8.40%. This usually indicates manageable turnover if performance and hiring quality remain strong.
Start 40, end 70, left 12. Average headcount is 55. Attrition is 21.82%. Even with growth, this can signal onboarding pressure or manager capacity issues.
Start 85, end 72, left 20. Average headcount is 78.5. Attrition is 25.48%. At this level, teams often face productivity drops, burnout, and recruitment bottlenecks.
Use this reference to classify outcomes and align retention response plans.
| Attrition Range | Typical Interpretation | Operational Impact | Recommended Action |
|---|---|---|---|
| 0%-8% | Low / stable | Minimal disruption | Maintain current retention playbook |
| 8%-15% | Moderate / watch | Manageable replacement load | Segment by manager and tenure |
| 15%-25% | High risk | Hiring strain and productivity drag | Targeted interventions + monthly review |
| 25%+ | Critical | Service, quality, and culture risk | Executive-level retention response |
Share it with HR teams tracking retention and staffing trends.
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