Turnover % = leavers ÷ average headcount over the window. Four departures against an average headcount of 40 is 10% for that window; measure over a rolling 12 months so seasonality doesn't fool you.
Two distinctions make the number actionable:
- Voluntary vs involuntary. People quitting and people being let go are different problems — one points at retention, the other at hiring.
- Regretted vs non-regretted. Losing a strong senior mid-project and parting with a mis-hire during probation should never land in the same bucket.
For an IT services company attrition costs more than the HR view suggests: revenue is people × time × rate, so a departing engineer is simultaneously a capacity gap, a handover project, a client-relationship risk, and a recruiting-plus-ramp-up bill. Attrition on billable roles hits utilization directly.
Read the trend, not the snapshot — a single quarter means little at a 20-person size, where one person is five percentage points. And always pair the rate with reasons: the number says that people leave; exit conversations say why.
In Helia, the dashboard's turnover widget computes the last 12 full months from hire and termination dates — joiners and leavers per month, turnover % as leavers ÷ average headcount — with a breakdown of offboarding reasons next to it, so the rate and the "why" sit on one screen.