Attrition Rate Calculator

Measure attrition against average headcount and see the annualised equivalent.

About Attrition Rate Calculator

The attrition rate is the share of average headcount that leavers in the period represents, expressed as a percentage. The same figure is also shown per 1,000 and as a "one in every N" odds statement, which is easier to reason about when the rate is very small. Absolute counts hide scale — a rate normalises the number so you can compare periods, channels or cohorts of different sizes, where lower is better.

Formula

Attrition Rate

Attrition Rate = Leavers in the period ÷ Average headcount × 100

Leavers in the period: The subset being measured
Average headcount: The full population it is drawn from

Worked example

With the default values below, Attrition Rate Calculator returns Attrition Rate of 14.17%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Leavers in the periodminimum 0: 34
Average headcountminimum 0: 240

Results

Attrition Rate: 14.17%
Remaining (whole minus part): 206
Equivalent per 1,000: 141.7
One in Every: 7.1

Step by step

1Values used
2Attrition Rate
3Attrition Rate= 14.17
4Remaining (whole minus part)= 206
5Equivalent per 1,000= 141.7
6One in Every= 7.1

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or fees or charges into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Attrition Rate calculated?

Attrition Rate = Leavers in the period ÷ Average headcount × 100 The attrition rate is the share of average headcount that leavers in the period represents, expressed as a percentage. The same figure is also shown per 1,000 and as a "one in every N" odds statement, which is easier to reason about when the rate is very small.

Why does Attrition Rate matter?

Absolute counts hide scale — a rate normalises the number so you can compare periods, channels or cohorts of different sizes, where lower is better.

What values do I need to enter?

This calculator takes 2 inputs: Leavers in the period, Average headcount. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.