Turnover describes the amount of employees coming and going from a business. There are different ways to calculate true and rolling turnover based on the period counted and the difference in the number of employees. Industries with high turnover tend to favor true turnover, while industries with very low turnover tend to be indifferent to the statistic.

Rolling Turnover

Rolling turnover calculates the turnover of employees averaged over a given period of time and includes new people that have come to the firm. The method for calculating rolling turnover is to first find the number of employees that left the company. Next, average the number of employees at the beginning of the period and at the end of the period. Finally, divide the number of employees leaving by the average total number. For example, image you had the following scenario over a six-month period: 10 employees left, 48 were employed at the beginning of the six-month period and 52 were employed at the end of the period. Your business' rolling turnover is 20 percent: Average equals (48 plus 52) divided by 2 equals 50; 10 divided by 50 equals a 20 percent rolling turnover.

True Turnover

True turnover, on the other hand, does not account for leaving employees in the same way. Instead, the true turnover only counts the difference in the number of employees at the beginning and the end of the period. Simply take the difference of the two numbers and divide by the ending period number. Using the same example, you had 48 at employees at the beginning of the six-month period, and 52 at employees at the end of the period; your true turnover is 8 percent: Difference equals 52 minus 48 equals 4; 4 divided by 52 equals an 8 percent true turnover.

Turnover Downside

Turnover can often impair productivity at a firm based on significant hosts of hiring and training new employees. Companies often strive to lower their turnover rates, especially in high turnover sectors, such as retail, restaurants and hospitality. These sectors often have much higher rolling turnover than true turnover.

Low Turnover

For firms or industries with extremely low growth, the true turnover and rolling turnover can be close to equal. For example, government sectors, such as public education, state government workers and federal government workers, have extremely low turnover rates. For these sectors, it is not as important to differentiate between true and rolling turnover, as both are extremely low.