Employee turnover is defined as the staff who leave your workforce over time. People may leave because they retire, resign, get fired, or transfer. Any reason counts towards employee turnover. The turnover rate is calculated by dividing the number of staff who leave by the annual average number of employees. Times the answer by 100 and you have your turnover rate as a percentage.
Employee turnover is one of the biggest costs that organizations encounter. You have to conduct a hiring process to replace them as well as the time spent on training the replacement. Factor in the loss of productivity during that time, the institutional knowledge lost, and the cost is massive.