The general trend to caculate attrition rate one would measure the rate at which employees are leaving a company.
Attrition rate can be calculated by dividing the number of employees who have left the company in a given period by the total number of employees present (before those employees have left). Employee attrition rate can be calculated on a monthly or yearly basis.
I hope this will clear out your doubts.
Attrition rate or turnover rate can be calculated on the basis of the following:
* It may be helpful to calculate your turnover rate and study trends in your ability to retain good employees. Turnover rate, calculated as a percentage, is determined by the following formula.
Number of employee separations for the period /
Number of employees at a fixed point during the period x 100
* The turnover rate can be further refined by removing unavoidable separations, such as death and retirement, from the calculation as in the following formula.
(Number of employee separations for the period - unavoidable separations) /
Number of employees at a fixed point during the period x100
* Another measure of employees exiting your organization is the attrition rate. This can be calculated on how many persons hired in a particular year, remain in following years. For example if you hired 100 people in October, 2003 and 80 were still employed in November of 2004, your survivor rate would be 80% and your attrition rate would be 20%.
The objective of examining your turnover rate is not to have the lowest number possible.
You would not want to retain an employee who has proved ineffective. Rather it is to monitor the rate at which employees are leaving your organization as well as the reasons employees are leaving.
Tracking the reasons people leave is typically accomplished through an exit interview.
Hope that would be of use for you. If any other query you have feel free to contact. :)