Attrition Rate Calculator

How to use the Attrition Rate Calculator#

1. Enter headcount. Use the number of employees at the start and at the end of the period.
2. Enter leavers. Count everyone who left, however they left.
3. Set the period. Use months. The yearly figure scales a shorter period to twelve months.

The formula#

With 200 people at the start and 190 at the end, average headcount is 195. If 25 left, attrition is 25 ÷ 195 = 12.8 percent, and retention is 87.2 percent.

Attrition and turnover#

The two words are often used loosely. Some teams call it attrition when a role isn’t refilled and turnover when it is. Others use them as synonyms. Whichever you use, apply it the same way each time so the trend means something.

Reading the number#

A single figure tells you little without context. Compare it with your own history, with other departments and with typical rates in your industry, which vary a lot. Split it by tenure and department. A high rate among new hires points to a different problem than a high rate among long-serving staff.

A worked example#

A company starts the year with 180 staff, ends with 168 and has 30 people leave. The average headcount is (180 + 168) ÷ 2 = 174. Attrition is 30 ÷ 174 = 17.2 percent, and retention is 82.8 percent. The same 30 leavers in six months would be annualised to 34.5 percent, which is why the calculator asks for the length of the period.

Voluntary, involuntary and avoidable#

The headline rate lumps together everyone who left. HR teams usually split it. Voluntary attrition covers resignations, involuntary covers dismissals and redundancies, and some roles that are not refilled count as reduction, not turnover. Avoidable attrition is the part you could have prevented, such as someone who left for pay or a poor manager. Exit interviews and a quick survey of leavers give you the reasons, and if the same reason keeps coming up, that is where to act.

The cost of losing people#

Replacing an employee costs recruiting fees, training time and lost output while the new person learns the job. Estimates often run from half to twice an annual salary, depending on the role. If you lose 30 people from a team where each costs ₦1,500,000 to replace, that is ₦45,000,000 a year. A lower attrition rate in the first year is usually the cheapest improvement, since new starters leave at the highest rate. For the staff budget, see the revenue calculator and the profit calculator.

Annualising a short period#

If 3 people leave a team of 100 in a month, monthly attrition is 3 percent. The calculator annualises that as 36 percent, by multiplying by 12. Compounded, the share of the original staff still there after a year would be 0.97¹² = 69.4 percent, which means about 30.6 percent have left. A single bad month, such as the one after annual bonuses are paid, can make a yearly figure look worse than it is, so look at a rolling twelve months.

What helps keep people#

Studies of exit interviews tend to find the same reasons: pay that is behind the market, no path to promotion, a poor relationship with a manager, workload and flexibility. Fixing pay is the most expensive and not always the most effective. Regular conversations about growth, clear goals, good onboarding in the first 90 days and managers who are trained to manage all help. Track attrition by team, length of service, age group and manager, since a company-wide number can hide a single department with a serious problem.

Last reviewed October 2026 by the Calclulo team.