Attrition Rate
The proportion of employees who leave over a period, expressed against average headcount.
Attrition rate is the number of employees who left during a period, divided by the average headcount over that period, expressed as a percentage. Average headcount is usually the mean of opening and closing headcount, though some organisations average monthly figures instead — which produces a different number from the same underlying data.
The definitional question that matters more than the arithmetic is what counts as a departure. Voluntary resignations, dismissals, redundancies, retirements and end-of-contract exits can all be included or excluded, and organisations differ. A rate quoted without saying which are counted is not comparable to anyone else’s.
Separating voluntary from involuntary attrition is usually the most useful single cut, because they have different causes and different remedies. A rising voluntary rate is a retention problem; a rising involuntary rate is usually a hiring or performance-management problem.
Annualising a rate from a short period magnifies ordinary variation. A quarter multiplied by four turns two unexpected resignations into an alarming headline, which is worth remembering before reporting one.
What varies
Organisation. There is no statutory or single authoritative definition — what counts as a departure, and how average headcount is derived, both differ.
Also called: employee turnover rate, staff turnover.
This is a description of the law as it stands, not legal advice. Back to the glossary.
In the product
HR Analytics
Workforce cost and attrition, without a data request.
- Live headcount, workforce cost and cost-per-hire dashboards
- Attrition analysis by department, tenure, manager and location
- Attendance, overtime and leave-liability trends