Attrition Rate Calculator
Calculate your employee attrition rate for any period from headcount and leaver data, with a voluntary and involuntary breakdown.
Calculation Examples
How to Use the Attrition Rate Calculator
Collect three numbers for the period you want to analyze: headcount at the start, headcount at the end, and the total number of employees who left.
If you want a voluntary breakdown, also record how many departures were resignations and how many were layoffs or dismissals. The voluntary figure is often the more useful one, because it shows losses you may be able to prevent, such as those driven by pay gaps, weak management, or lack of career growth.
Choose a monthly or annual period. The calculator divides leavers by the average of start and end headcount, which smooths out hiring waves and layoffs inside the period. This is the standard separations-over-average-headcount method that HR teams use for turnover reporting, so your figures stay comparable from period to period.
The Mathematics of Attrition Rate Calculations
The calculation takes two steps. First, find the average headcount: \[\text{Average Headcount} = \frac{\text{Headcount}_{\text{start}} + \text{Headcount}_{\text{end}}}{2}\] Then divide leavers by it: \[\text{Attrition Rate (\%)} = \frac{\text{Total Leavers}}{\text{Average Headcount}} \times 100\]
Average headcount matters most when the workforce changes size. A company that grows from 100 to 140 employees and loses 15 people has an average headcount of 120, so the attrition rate is 12.5%. Dividing by the starting 100 gives 15%, which overstates attrition by 20%.
To annualize a monthly rate, multiply by 12, and for a quarterly rate, multiply by 4. A team with an average headcount of 120 that loses 3 people in a month has a monthly rate of 2.5%, which annualizes to 30%. Treat annualized figures from a single month as a rough guide, since one resignation wave can distort them.
Useful Tips 💡
- Exclude seasonal contractors and temporary workers from headcount if you want the figure to describe your permanent workforce only.
- Take headcount snapshots on the same day each month, for example the first working day, so periods stay comparable.
📋Steps to Calculate
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Enter the total employee headcount at the start of the reporting period.
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Enter the total employee headcount at the end of the reporting period.
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Enter the total number of leavers, and separately the number of voluntary resignations if you have it.
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Click Calculate to see the attrition rate, average headcount, and voluntary attrition share.
Mistakes to Avoid ⚠️
- Dividing by starting headcount instead of the average, which overstates attrition when headcount has grown and understates it when headcount has shrunk.
- Leaving out employees who joined and left within the same period, which understates true turnover where hiring volume is high.
- Mixing up attrition and turnover: some HR teams use attrition for exits that are not backfilled and turnover for all exits, but usage varies, so define the term in every report.
- Showing a monthly rate to leadership without annualizing it, which makes the yearly workforce impact look about 12 times smaller.
Practical Applications📊
Flag departments where annualized attrition runs well above your company average and look into retention steps there.
Match voluntary attrition spikes with exit interview themes to find root causes in pay, management, or culture.
Forecast hiring needs: with 205 average headcount and 7.3% attrition per half-year, expect about 30 exits a year, so plan for about 30 backfills before any growth.