Attrition Rate Calculator
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.
Result
Attrition rate
15.65%
Attrition = L / ((S + E) / 2) × 100%
Average headcount
115 ( (start + end) / 2 )
Employees left
18
What This Calculator Measures
Output
Attrition rate (%)
Key input
(Start + End) / 2
Use case
Workforce planning
Quick Example
Start = 120, End = 110, Left = 18
Average headcount
115
Attrition rate
15.65%
How to Calculate Attrition Rate
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.
Formula
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.
Tips for clean reporting
- Use consistent counting rules (who counts as “left” and what dates apply).
- Compare like-for-like timeframes (e.g. month-to-month or quarter-to-quarter).
- Segment by department, role, and tenure to find where attrition is concentrated.
- Pair attrition with context: hiring volume, absenteeism, and workload indicators.
Frequently Asked Questions
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