The rate at which employees leave an organisation over a given period, expressed as a percentage.
Attrition rate measures the proportion of an organisation's workforce that leaves over a defined period, usually a year. It is the headline retention metric on most HR dashboards, and also one of the most frequently miscalculated — the arithmetic is simple, but the choice of denominator, period and population changes the answer enough to make two teams reporting "the same" figure disagree by several points.
Attrition rate is leavers divided by average headcount, expressed as a percentage. The word doing the work is average. Dividing by opening headcount flatters a growing company and punishes a shrinking one; dividing by closing headcount does the reverse. Averaging the two — or better, averaging monthly headcounts across the period — keeps the figure comparable as the organisation changes size.
Attrition rate % = (leavers during the period ÷ average headcount during the period) × 100
A company starts the year with 180 employees and ends with 220, and 34 people leave during the year. Average headcount is (180 + 220) ÷ 2 = 200, so attrition is 34 ÷ 200 = 17%. Had the same 34 leavers been divided by the closing headcount of 220, the rate would read 15.5%; against the opening 180 it would read 18.9%. Nothing about the business changed — only the denominator did.
A single blended number hides the thing you actually want to know. Voluntary attrition (people choosing to leave) and involuntary attrition (redundancy, dismissal, end of fixed term) have opposite implications: a restructure can push the headline rate up while voluntary attrition is falling. Splitting the two is the minimum useful breakdown.
The more valuable split is regretted versus non-regretted — whether you wanted to keep the person. An organisation with 18% attrition where almost none of it is regretted is in better shape than one at 9% losing its strongest performers. Because that judgement is made by managers rather than derived from a system, it needs a deliberate field at exit rather than a report.
There is no universal benchmark worth quoting, and we deliberately do not publish one here. Published averages differ by sector, country, seniority and — most of all — by how the survey defined a leaver, so comparing your rate against a headline national figure usually compares two different measurements. The comparison that carries information is against your own trend, segmented: by team, tenure band, manager and hiring cohort. A stable 14% that is concentrated entirely in first-year hires is a recruitment or onboarding problem wearing a retention costume.
They are used interchangeably by most HR teams and calculated identically. Where organisations do distinguish them, attrition tends to mean departures a company does not backfill, while turnover covers all departures including those replaced. Define which you mean in your own reporting, because the two readings can diverge sharply during a hiring freeze.
Include them, but report them within involuntary attrition rather than the headline figure. A business with heavy seasonal or project-based hiring will otherwise appear to have a retention crisis every time a cohort of contracts reaches its planned end.
Explore our full platform with a 14-day free trial on Standard. Manage employees, post jobs, hire faster, and manage your tasks effortlessly with our all-in-one platform.