Attrition rate (also called employee attrition or staff turnover) measures the rate at which employees leave the organisation. It encompasses all departures — voluntary (resignations), involuntary (layoffs, terminations), and natural (retirement) — though organisations often track these categories separately to distinguish controllable from uncontrollable attrition.
The standard calculation is: (Number of departures in the period ÷ Average headcount during the period) × 100. For example, if a company has an average of 200 employees and 30 leave in a year, the annual attrition rate is 15%.
Attrition rate directly determines minimum hiring volume. An organisation with 500 employees and 20% annual attrition must hire at least 100 people per year simply to maintain headcount — before any growth-driven hiring is added. Understanding and forecasting attrition is therefore a prerequisite for accurate headcount planning.
Regrettable attrition — the departure of employees the organisation wanted to retain, particularly high performers — is the most strategically significant component. An overall 15% attrition rate is very different in its impact depending on whether the departures are predominantly low performers or high performers. Tracking attrition by performance category reveals the true health of the retention strategy.
Key Points: Attrition Rate
- Standard formula: (Departures ÷ Average headcount) × 100 = attrition rate as a percentage.
- Voluntary vs involuntary: Separating voluntary resignations from managed exits reveals the controllable component of attrition.
- Regrettable attrition: High-performer attrition is far more damaging than average-performer attrition — track by performance category.
- Headcount planning driver: Attrition rate directly determines the minimum hiring volume required to maintain organisational size.
- Benchmark context: Industry and role-type benchmarks provide essential context — a 25% rate in retail is normal; in finance it is alarming.
How Attrition Rate Works in Treegarden
Attrition Rate in Treegarden
Treegarden's HR analytics track attrition rates by department, level, tenure cohort, and time period. When the ATS and HR modules are used together, the platform can calculate quality-of-hire metrics by tracing retention outcomes back to the recruiting records of each hire — revealing whether certain sourcing channels, hiring managers, or recruiting processes are associated with higher attrition.
Related HR Glossary Terms
Frequently Asked Questions About Attrition Rate
What constitutes a healthy attrition rate varies enormously by industry, role type, and organisational context. In high-turnover sectors like retail, fast food, and call centres, annual attrition rates of 50-100%+ are common and expected — the business model is built around high volume hiring. In professional services, technology, and finance, rates of 10-20% are typical. In government and education, 5-10% is common. Healthcare falls somewhere in between and varies significantly by role type and setting. The most meaningful benchmark is the trend within your own organisation over time — is attrition increasing or decreasing, and what is driving the change? — combined with comparison to direct industry peers rather than all-industry averages that mix incomparable sectors.
The terms are often used interchangeably in practice, though technical distinctions exist. Attrition typically refers to the reduction of the workforce through departures that are not replaced — the organisation intentionally reduces headcount through natural departures rather than active layoffs. Turnover refers to the rate at which employees leave and are replaced — the workforce size remains constant because departures are backfilled with new hires. In practice, most HR analytics use 'attrition' and 'turnover' to mean the same thing: the rate at which employees leave the organisation, regardless of whether replacements are hired. The context in which a specific definition is applied should be established explicitly in any analytics framework to prevent confusion in cross-functional discussions about workforce metrics.
Segmented attrition calculation follows the same formula as overall attrition but applied to a specific subset of the workforce. For department-level attrition: count the number of departures from that department in the period and divide by the average headcount of that department during the period. For cohort attrition (e.g., employees hired in 2024): count how many of that cohort have departed and divide by the original cohort size. Cohort analysis is particularly valuable because it reveals attrition patterns over the employee lifecycle — if 40% of employees hired in the same year leave within 24 months, that is an onboarding and early engagement problem that cohort analysis identifies clearly. Benchmarking cohort attrition across hiring sources (do referral hires stay longer than job board hires?) connects retention data back to recruiting decisions.
High voluntary attrition is consistently driven by a predictable set of factors that employee engagement and exit interview research has identified across industries. Compensation below market rate is the most commonly cited reason for departure, particularly when employees become aware of compensation gaps through external offers or salary transparency tools. Lack of career development and advancement opportunity is the second most common driver — employees who cannot see a clear path forward leave for organisations that offer it. Poor management is consistently cited: a bad relationship with a direct manager drives departure even when other factors are positive. Toxic work culture — lack of respect, excessive politics, or values misalignment — has become an increasingly prominent driver, particularly among younger workers. Finally, burnout from sustained overwork accelerates departure in organisations that consistently expect unsustainable workloads without adequate resourcing.