How to Calculate Attrition Rate: Formula, Examples, and Benchmarks

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 added up to 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. The harder part is 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.

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 you are losing people faster than is healthy for the business. 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. That is why a small business owner needs to track attrition with more precision, not less.

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. Averaging allows for a team that grows or shrinks during the period as people join and leave. 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 stand out in this example. First, one quarter does not make a trend. At small scale the rate swings hard, and one bad quarter can be an anomaly, so track at least two consecutive quarters before concluding you have a systemic problem.

Second, the breakdown matters more than the total. The 2 voluntary departures (people chose to leave) and the 1 involuntary (you made the decision) tell different stories, and 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 can arrive at 14% and 31%. There is no universal standard here, so what matters is choosing a convention, writing it down, and applying it the same way every period, because a change in method looks exactly like a change in performance.

Part-time employees create a second decision: count them by headcount or by FTE (full-time equivalent). 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 method is defensible. Mixing them is not, and it happens all the time: 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.

That is three numbers from the same twelve months, all correctly calculated, ranging from 33% to 150%. No single formula is the right one here. What the example shows is that a rate means nothing unless you state the population and the method alongside it.

Choosing between the two methods comes down to how your headcount moves. If it 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 annual rate, multiply by 12: a monthly rate of 1.5% becomes roughly 18% a year. That matches the count-based annual formula above and the way BLS builds its annual separation totals, by adding up the 12 monthly separation counts rather than compounding them.

A compounding estimate, 1 - (1 - Monthly Rate)^12, puts the same 1.5% at about 16.6%. It assumes each month's leavers come out of a shrinking original group, so it can never exceed 100%, even when the same seats turn over again and again, as in the restaurant example above. For attrition, stick with the multiplication.

Types of Attrition

The table below splits attrition into five types: voluntary, involuntary, regrettable, early, and retirement. They are not equal, and splitting departures this way tells you which type to address and which to accept.

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.

Early attrition matters more than overall attrition for a small business because every early departure wastes the whole recruiting investment (job posting, interviewing, offer negotiation) and the whole onboarding investment (training time, setup, manager attention) with zero productive return. An employee who leaves after two years at least contributed for 22 months. One 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 six columns: five you fill in and one formula.

The common mistake is keeping 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.

With the period start and end dates in cells H1 and H2, every metric becomes a COUNTIFS formula, the spreadsheet function that counts rows meeting several conditions at once. 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 between the period start and 90 days before the period end whose employment lasted 90 days or fewer, the same cohort the denominator below uses. The extra condition that days employed be zero or more keeps active employees, whose cell in that column is blank, out of the count:

=COUNTIFS(C:C,">="&$H$1,C:C,"<="&$H$2-90,F:F,"<=90",F:F,">=0")

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.

Tenure at exit is the cut that pays for itself fastest. 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.

Here is the whole thing as a starter file. The log is the substrate, the two summary tabs turn it into the rates, and the last tab is where you record the conventions from the edge-case section so that next quarter's number is comparable to this one.

Fill in the method record before you calculate anything. It takes five minutes once, and it is the only thing standing between a rate that means something and two people arguing about whether the number went up.

The Attrition Metrics Worth Reporting Each Quarter

A useful attrition report is five numbers, not fifty: the headline rate with the method that produced it, the voluntary and involuntary split, early attrition with its cohort dates, departures grouped by manager or department, and the tenure bucket each leaver fell into.

Those five answer the questions people actually ask in the meeting: whether the rate is worse than last quarter, whether staff are choosing to leave or being let go, whether the losses sit with new hires, whether one team is producing most of them, and whether departures land at a predictable point in the tenure curve.

Report the same five every period, in the same order, with the method note attached. A report that changes shape each quarter cannot show a trend, and the trend is the only part of an attrition number that has ever changed a decision I made.

Attrition vs Turnover: What Is the Difference?

Attrition and turnover are closely related but technically different: attrition traditionally means departures whose positions are not immediately refilled, while turnover counts every departure, including the ones you replace. In practice, many HR professionals use the terms interchangeably, and the formula is identical. The distinction matters when you are analyzing whether your headcount is growing, shrinking, or staying flat.

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

The only benchmark worth comparing yourself against is one you can trace to a source. The Bureau of Labor Statistics publishes turnover monthly in the Job Openings and Labor Turnover Survey, split by establishment size class and by industry. Every figure in the two tables below comes from it.

Two caveats before you read them. JOLTS counts establishments, which the BLS Handbook of Methods defines as generally a single physical location, so a chain's branch lands in the same size class as an independent shop. And BLS publishes these as monthly rates; the annualized column is that monthly rate multiplied by twelve, which makes it directional rather than exact.

Treat the tables as a way to work out whether your rate is normal for your industry, not as a target to hit. Read them next to the rest of the HR benchmarks you track, because a separations rate on its own never says why anyone left.

Source: BLS JOLTS table 7, seasonally adjusted, July 2026.

Source: BLS JOLTS 2025 annual average rates by industry, separations and quits, annualized the same way.

The size table contradicts a claim repeated all over the internet, which is that small businesses churn hardest. On the BLS numbers the smallest establishments separate less often than any class below 5,000 employees. What is true is that a small employer feels each departure far more, because one person is a double-digit share of the team.

If your rate is below the benchmark for your size and industry, your retention is working well. If it is above, 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. According to Gallup, replacing an employee costs one-half to two times that person's annual salary, and Gallup calls that a conservative estimate.

Building the number from the bottom up, one line at a time from your own records, shows where your business sits inside that band.

At a 15-person company with a 20% annual attrition rate and an average salary of $50,000, you lose 3 people per year. On Gallup's band that is $75,000 to $300,000 in annual replacement costs, or the equivalent of 1.5 to 6 extra salaries spent replacing people rather than growing the team.

Onboarding is where most of that money is recoverable. Gallup finds employees are 3.4 times as likely to call their onboarding successful when their manager takes an active part in it, and manager attention costs nothing except calendar time.

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 actions that give the highest return on investment (ROI).

The first strategy, structured onboarding, has the highest ROI because early attrition is both the most expensive kind per departure, with zero productive return, and the most fixable, since a structured first 90 days can be implemented in a week.

Whatever else you add, build your retention strategies into the onboarding process from Day 1, and treat the first 90 days as the foundation of the employee relationship rather than a compliance exercise.

If you do one thing after reading this, set up the tracker, fill in the method record, and calculate early attrition for your most recent complete cohort of hires. That single number tells you whether onboarding is where your departures, and your money, are leaking.

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