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.
Who Counts as a Leaver? The Edge Cases That Change Your Number
The formula is trivial. Deciding who belongs in the numerator is where two people calculating the same company's attrition arrive at 14% and 31%. There is no universal standard here, which means the only thing that matters is choosing a convention, writing it down, and applying it the same way every period. A change in method is indistinguishable from a change in performance.
| Situation | Standard treatment | Why |
|---|---|---|
| Seasonal or fixed-term hires whose assignment ended as planned | Exclude from the headline rate; report separately | A business that staffs up for summer and releases the crew in October will show catastrophic attrition that reflects the business model, not a retention problem |
| Interns and co-op students | Exclude from both numerator and denominator | Their departure was scheduled before they started; including them inflates the rate and hides real losses |
| Independent contractors and 1099 workers | Exclude entirely | They are not employees. Counting them also distorts every other per-employee metric you report |
| Someone who resigns and is rehired four months later | Count the separation when it happens and the rehire as a new hire | Do not net them out. The seat was empty, the work was disrupted, and the cost was real |
| An employee terminated during a probationary period | Count as involuntary and also as early attrition | It belongs in both cuts. Probationary terminations usually indicate a hiring or onboarding failure, not a performance mystery |
| A reduction in force or layoff | Count as involuntary, and report the rate both with and without it | One RIF can swamp a year of trend data. Executives need to see the underlying voluntary rate underneath it |
| Death or permanent disability | Count as an other or unavoidable departure | It is a real loss of headcount but tells you nothing about retention. Never put it in the voluntary bucket |
| Retirement | Count as a departure, tracked in its own category | Retirements are foreseeable and belong in succession planning, not in your engagement diagnosis |
| An employee on FMLA, parental, or medical leave at period end | Still employed: count in headcount, not as a leaver | They have not separated. Only count them if and when they fail to return |
| A move between locations or departments under the same employer | Not a departure | Internal transfers are mobility, not attrition. If the legal employer or EIN changes in a restructuring, decide once and document it |
| A contractor converted to a W-2 employee | Count as a new hire on the conversion date, with no separation | Their tenure clock for retention purposes starts at conversion unless you deliberately credit prior service |
Part-time employees create a second decision: headcount or FTE. Under a headcount method, a 20-hour-per-week employee counts as one person in both the numerator and the denominator. Under an FTE method, they count as 0.5 in both. Either is defensible. Mixing them is not, and mixing them is common: counting three part-time leavers as three departures while dividing by an FTE denominator will overstate your rate.
Getting Average Headcount Right
The (start + end) / 2 method assumes your headcount moved in a straight line between the two dates. Over a month, that assumption is harmless. Over a year, in a business that hires in bursts or staffs seasonally, it can be badly wrong, because the two endpoints are the only two data points the method ever looks at.
Three numbers from the same twelve months, all correctly calculated, ranging from 33% to 150%. The lesson is not that one formula is right. It is that a rate is meaningless without the population and the method stated alongside it. If your headcount is stable and you hire steadily, the endpoint method is fine and takes seconds. If you hire in waves, staff seasonally, ran a layoff, or grew more than about 20% during the period, use monthly averages instead.
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).
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.
How to Calculate Attrition Rate in a Spreadsheet
You do not need an analytics tool to run every calculation in this guide. You need one table with one row per employee who has ever worked for you, and four columns filled in correctly. The common mistake is maintaining a separate list of people who left, which drifts out of sync with payroll within two quarters. Keep one table, never delete a row, and let formulas do the counting.
| Column | Contents | Notes |
|---|---|---|
| A | Employee name or ID | One row per person per period of employment. A rehire gets a second row, not an edited first row |
| B | Department or manager | This is the column that turns a company-wide number into a diagnosis |
| C | Hire date | Must be a real date value, not text. Sort by this column once to catch anything typed as text |
| D | Termination date | Left blank while the person is active. Blank is the flag the formulas rely on |
| E | Departure type | Voluntary, Involuntary, Seasonal, Retirement, Other. Use a dropdown so the spelling never varies |
| F | Days employed | A formula, not a typed number: =IF(D2="","",D2-C2) |
With period start and end dates in cells H1 and H2, every metric becomes a single COUNTIFS. Headcount on a given date is anyone hired on or before that date who either has no termination date or terminated after it:
=COUNTIFS(C:C,"<="&$H$1,D:D,"") + COUNTIFS(C:C,"<="&$H$1,D:D,">"&$H$1)
Departures during the period, and the voluntary-only version, are simpler:
=COUNTIFS(D:D,">="&$H$1,D:D,"<="&$H$2)=COUNTIFS(D:D,">="&$H$1,D:D,"<="&$H$2,E:E,"Voluntary")
Early attrition needs the days-employed column. The numerator counts people hired during the period whose employment lasted 90 days or fewer, and the extra lower-bound criterion keeps the blanks for active employees out of the count:
=COUNTIFS(C:C,">="&$H$1,C:C,"<="&$H$2,F:F,"<=90",F:F,">=0")
=COUNTIFS(C:C,">="&$H$1,C:C,"<="&$H$2-90). Then report the cohort dates alongside the percentage, because "25% of our Q1 hires" and "25% of hires made before December 15" are different claims.Once the table exists, segmentation costs nothing. Add a department criterion to any of the formulas above, or build a pivot table with department in rows and a count of termination dates in values. The cut that pays for itself fastest is tenure at exit: bucket the days-employed column into 0-90 days, 91-365 days, 1-2 years, and 2 years or more, then count departures in each bucket. A pile in the first bucket is a hiring or onboarding failure. A pile in the 1-to-2-year bucket is almost never about pay, and almost always about the absence of a visible next step.
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 one place the wording does carry weight is natural attrition, where you deliberately leave a role unfilled after someone retires or resigns and let headcount shrink on purpose.
Attrition Rate vs Retention Rate: They Do Not Add Up to 100
A board member or investor will eventually ask for your retention rate, and the instinct is to subtract your attrition rate from 100. That answer is almost always wrong, because the two metrics look at different populations. Attrition counts every departure against your average headcount, including new hires who arrived and left inside the same period. Retention asks a narrower question: of the people who were here when the period started, how many are still here now?
This is why retention rate on its own can flatter a business that is churning through new hires: the metric structurally ignores them. It is also why the two numbers belong together in any report. Retention tells you whether your established team is stable. Attrition tells you what the whole population cost you. When retention looks healthy and attrition looks bad, the problem is concentrated in people who never made it through their first year, and the fix lives in hiring and onboarding rather than in anything you would do for your tenured staff.
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. If the departures cluster at the one- to two-year mark, look at internal mobility first: creating a visible next step inside the company removes the main reason people who like the job still leave it.
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.
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).
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.
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.