How to Calculate Attrition Rate: Formula, Examples, and Benchmarks
How to calculate attrition rate with the standard formula. Step-by-step examples, monthly and annual formulas, and benchmarks by company size.
How to Calculate Attrition Rate
Formula, examples, and benchmarks for small businesses
I did not start tracking attrition until after my third employee quit in the same quarter. Until then, each departure felt like an isolated event: one person got a better offer, one did not like the role, one had a personal situation. Three in one quarter at a 14-person company was not a series of coincidences. It was a 21% quarterly attrition rate, and when I ran the numbers, the cost was somewhere between $75,000 and $150,000 in recruiting, onboarding, and lost productivity.
The formula itself takes 30 seconds. Understanding what the number means, how to break it down by type, how your rate compares to benchmarks for your size, and which segment of attrition you can actually control takes longer. This guide covers the standard attrition rate formula, step-by-step calculation with a worked example, monthly and annual variations, the difference between attrition types, benchmarks by company size and industry, the cost math, and the specific type of attrition that small businesses can most effectively reduce: early attrition in the first 90 days, which connects directly to FirstHR's core mission of structured onboarding.
What Is Attrition Rate?
Attrition rate is the percentage of employees who leave a company during a specific time period. It measures the rate at which people exit, regardless of whether those positions are refilled. A high attrition rate means people are leaving faster than you can retain them. A low rate means your team is stable.
For small businesses, attrition rate matters more per departure than at large companies because each person represents a larger percentage of the team. At a 10-person company, one departure is 10% attrition. At a 1,000-person company, one departure rounds to zero. This means small business owners need to track attrition with more precision, not less, because each data point carries more weight.
The Attrition Rate Formula
The formula has two inputs: the number of employees who left during your chosen period, and the average headcount during that same period. Average headcount accounts for the fact that your team size may change during the period due to hires and departures. Using start-of-period headcount alone would overstate the rate if you hired during the period. Using end-of-period headcount alone would understate it.
Step-by-Step: How to Calculate Attrition Rate
Worked Example for a Small Business
Two things to note from this example. First, one quarter does not make a trend. Small businesses are inherently volatile: one bad quarter can be an anomaly. Track for at least two consecutive quarters before concluding you have a systemic problem. Second, the breakdown matters more than the total: 2 voluntary departures (people chose to leave) and 1 involuntary (you made the decision) tell different stories. Voluntary attrition is the metric you want to focus on reducing. The turnover reduction guide covers the specific strategies.
Monthly, Quarterly, and Annual Attrition Formulas
The formula is identical across all time periods. Only the inputs change: you count departures and headcount for the specific period you are measuring.
To convert a monthly rate to an approximate annual rate, multiply by 12. A monthly rate of 1.5% translates to roughly 18% annually. For precise conversion, use the compounding formula: Annual Rate = 1 - (1 - Monthly Rate)^12. At small scale, the simple multiplication is close enough for practical decision-making.
Types of Attrition
Not all attrition is equal. Breaking departures into categories tells you which type to address and which to accept.
| Type | Definition | Formula Modification | What It Tells You |
|---|---|---|---|
| Voluntary | Employee chose to leave (resignation) | Use only voluntary departures as numerator | Whether people want to stay. The most important metric to reduce. |
| Involuntary | Company initiated the departure (termination, layoff) | Use only involuntary departures as numerator | Whether you are hiring well and managing performance effectively. |
| Regrettable | A voluntary departure you wish had not happened (high performers, hard-to-replace roles) | Use only regrettable departures as numerator | Whether you are losing the people who matter most. |
| Early (90-day) | Any departure within the first 90 days of employment | New hires who left in 90 days / Total new hires | Whether your onboarding is working. The most actionable metric for small businesses. |
| Retirement | Employee left due to planned retirement | Use only retirements as numerator | Whether succession planning is needed. Less relevant for SMBs. |
For small businesses, track three of these: total attrition (the headline number), voluntary attrition (the number you want to reduce), and early attrition (the number you can most directly improve through better onboarding). The people management guide covers the management practices that reduce voluntary attrition specifically. For the offboarding process that documents departures properly, the offboarding checklist covers every step.
Early (90-Day) Attrition: The Metric Small Businesses Should Track First
Early attrition measures the percentage of new hires who leave within their first 90 days. This is the single most actionable attrition metric for small businesses because it directly reflects the quality of your onboarding process, and onboarding is something you can fix in weeks, not months.
Why early attrition matters more than overall attrition for small businesses: every early departure represents a complete waste of the recruiting investment (job posting, interviewing, offer negotiation) plus the onboarding investment (training time, setup, manager attention) with zero productive return. An employee who leaves after two years at least contributed for 22 months. An employee who leaves after two weeks contributed almost nothing. The 30-60-90 day plan guide provides the framework that reduces early attrition by giving new hires structure, clarity, and support during the critical first months. The new employee performance review guide covers the milestone reviews that catch disengagement before it becomes a resignation.
Attrition vs Turnover: What Is the Difference?
Attrition and turnover are closely related but technically different. In practice, many HR professionals use them interchangeably, and the formula is identical. The distinction matters when you are analyzing whether your headcount is growing, shrinking, or staying flat.
| Dimension | Attrition | Turnover |
|---|---|---|
| Definition | Employees leave and the positions are not immediately refilled | Employees leave and are replaced (position continues to exist) |
| Effect on headcount | Headcount shrinks over time | Headcount stays stable (departures offset by new hires) |
| Calculation | (Departures / Avg Headcount) x 100 | (Departures / Avg Headcount) x 100 |
| Common usage | Often used for natural reduction (retirements, role eliminations) | Often used for all departures regardless of replacement |
| In practice at small businesses | The terms are used interchangeably | The terms are used interchangeably |
For a small business, the practical distinction rarely matters. What matters is tracking departures by type (voluntary, involuntary, early) and understanding the cost and cause of each. The HR processes guide covers how attrition tracking fits within the broader set of HR processes every small business needs. The complete HR guide covers the seven core functions where retention management sits within the HR lifecycle.
Attrition Rate Benchmarks by Company Size and Industry
Comparing your attrition rate to benchmarks helps you determine whether your rate is a problem or is normal for your size and industry. Two important caveats: benchmark data is heavily weighted toward companies with 100+ employees, and rates vary significantly by industry. Use these numbers as directional guides, not precise targets.
| Company Size | Typical Annual Attrition | Why |
|---|---|---|
| 1-10 employees | 25-35% (but volatile) | One departure creates a huge percentage swing; data is noisy |
| 11-25 employees | 20-28% | Limited growth paths, founder-dependent culture, less competitive benefits |
| 26-50 employees | 18-25% | Starting to formalize processes; still higher than enterprise due to scale limitations |
| 51-100 employees | 15-22% | More structure, more management layers, more career paths |
| 100-500 employees | 12-18% | Approaching enterprise norms with formal HR processes |
| 500+ employees | 10-15% | Full HR infrastructure, competitive benefits, multiple career paths |
| Industry | Typical Annual Attrition (US) | Key Driver |
|---|---|---|
| Technology | 18-22% | High demand for talent, frequent job-hopping culture |
| Healthcare | 15-20% | Burnout, high-stress environments, shift work |
| Retail and hospitality | 25-35% | Low wages, seasonal work, limited advancement |
| Professional services | 12-18% | Project-based work, up-or-out cultures |
| Manufacturing | 15-20% | Physical demands, shift schedules, wage competition |
| Financial services | 10-15% | Competitive compensation, strong retention programs |
If your rate is below the benchmark for your size and industry, your retention is working well. If your rate is above the benchmark, dig into the type breakdown: is it voluntary or involuntary? Is it concentrated in the first 90 days (onboarding problem) or after 1 to 2 years (growth opportunity problem)? The answer determines the fix. The small business HR guide covers the broader retention infrastructure. The internal mobility guide covers how creating growth opportunities internally reduces the voluntary attrition that comes from employees feeling stuck.
The Cost of Attrition
The true cost of each departure extends far beyond the obvious expenses of recruiting and hiring the replacement.
| Cost Category | Typical Range | Example at $50K Salary |
|---|---|---|
| Recruiting (job posting, screening, interviewing) | 10-30% of annual salary | $5,000-$15,000 |
| Onboarding and training (the replacement) | 10-20% of annual salary | $5,000-$10,000 |
| Lost productivity (vacancy period + ramp-up) | 25-75% of annual salary | $12,500-$37,500 |
| Manager time (interviewing, onboarding, coaching) | 5-15% of annual salary | $2,500-$7,500 |
| Knowledge loss and team disruption | 5-25% of annual salary | $2,500-$12,500 |
| Total per departure | 50-200% of annual salary | $25,000-$100,000 |
At a 15-person company with a 20% annual attrition rate and an average salary of $50,000, you lose 3 people per year. At $25,000 to $100,000 per departure, that is $75,000 to $300,000 in annual replacement costs. For perspective, that is roughly equivalent to 1.5 to 6 full additional salaries spent on replacing people rather than growing the team. Organizations with strong onboarding see 82% better retention (Gallup), which directly reduces this cost. The HR automation guide covers how automating onboarding workflows specifically targets these high-cost early departures.
How to Reduce Attrition at a Small Business
Different types of attrition require different interventions. The strategies below are ordered by impact for small businesses, starting with the highest-ROI actions.
| Strategy | Which Attrition Type It Reduces | Expected Impact |
|---|---|---|
| Structured onboarding with 30-60-90 day milestones | Early (90-day) attrition | Reduces early departures by 50-82% depending on starting quality |
| Regular 1-on-1s with check-in questions | Voluntary attrition (year 1-2) | Catches disengagement before it becomes a resignation |
| Clear role definitions and expectations | Early attrition + voluntary | Prevents the 'this is not what I signed up for' departure |
| Competitive compensation review (annual) | Voluntary attrition | Addresses the #2 reason people leave after career growth |
| Career growth conversations (quarterly) | Voluntary attrition (year 2+) | Addresses the #1 reason people leave: lack of development |
| Exit interviews for every departure | All types (future prevention) | Reveals patterns you cannot see from the inside |
The first strategy (structured onboarding) has the highest ROI because early attrition is the most expensive per departure (zero productive return) and the most fixable (a structured first 90 days can be implemented in a week). The onboarding checklist provides the task list, the check-in questions guide provides the conversation framework, and the training plan guide covers skill-building during the critical early months.
For a comprehensive approach to retention, SHRM recommends integrating retention strategies into the onboarding process from Day 1, treating the first 90 days as the foundation of the employee relationship rather than a compliance exercise. The employee empowerment guide covers how giving people ownership over their work reduces voluntary attrition by addressing the underlying reason most people leave: feeling stuck.
Frequently Asked Questions
What is the formula for attrition rate?
Attrition Rate (%) = (Number of Employees Who Left During a Period / Average Number of Employees During That Period) x 100. For example, if 3 people left during a quarter and your average headcount was 25, your attrition rate is (3 / 25) x 100 = 12%. The average headcount is calculated as (headcount at start of period + headcount at end of period) / 2.
What is a good attrition rate?
A good annual attrition rate depends on your industry and company size. The average across all US industries is roughly 12-15% annually. For small businesses under 100 employees, rates tend to be higher at 20-26% because smaller teams are more sensitive to individual departures. Technology companies average 18-22%. Healthcare averages 15-20%. Retail and hospitality average 25-35%. Any rate below your industry average is considered good.
What is the difference between attrition and turnover?
Attrition and turnover both measure employee departures, but attrition traditionally refers to departures that are not immediately replaced (the position is eliminated or left unfilled), while turnover refers to all departures including those where the position is refilled. In practice, many HR professionals use the terms interchangeably. The calculation formula is identical for both. The distinction matters most when analyzing whether your headcount is growing, shrinking, or staying stable.
How do you calculate monthly attrition rate?
Monthly Attrition Rate (%) = (Number of Employees Who Left During the Month / Average Number of Employees During the Month) x 100. Use headcount at the start and end of the specific month to calculate the average. To annualize a monthly rate, you can multiply by 12 for a rough estimate, though compounding makes the actual annual rate slightly different. A monthly rate of 1.5% translates to roughly 16.5% annually when compounded.
How do you calculate early attrition (90-day attrition)?
Early Attrition Rate (%) = (Number of New Hires Who Left Within 90 Days / Total Number of New Hires During the Same Period) x 100. For example, if you hired 8 people in a quarter and 2 of them left within their first 90 days, your early attrition rate is (2 / 8) x 100 = 25%. This metric is specifically useful for evaluating onboarding effectiveness because it isolates departures that happen before employees are fully integrated.
How much does employee attrition cost?
The cost of replacing an employee ranges from 50% to 200% of their annual salary depending on the role. For a small business paying an average salary of $50,000, each departure costs $25,000 to $100,000 when you factor in recruiting, onboarding, training, lost productivity during the vacancy, and the ramp-up period for the replacement. At a 10-person company with 20% attrition, that is 2 departures per year costing $50,000 to $200,000 in total replacement costs.
Why is attrition rate higher at small businesses?
Small businesses typically have higher attrition rates for several reasons: fewer career advancement opportunities (limited management positions), less competitive benefits packages, higher sensitivity to individual departures (one person leaving a 10-person team is 10% attrition), less structured onboarding (which drives early attrition), and founder-dependent culture that can be volatile. The most controllable factor is onboarding: structured onboarding reduces early attrition significantly.
How often should I calculate attrition rate?
Calculate attrition rate quarterly at minimum. Monthly calculations are useful for spotting trends quickly but can be noisy at small companies where one departure creates a large percentage swing. Annual calculations are standard for benchmarking but too infrequent for catching problems early. The most practical approach for a small business: calculate monthly, review quarterly, benchmark annually.