Operating leverage is used to determine how a change in sales revenue affects the operating income of a company.
There are many ways of finding operating leverage. One of them is to denote it by ratio of the contributing margin ratio and the operating margin. This is called the degree of leverage or DOL.
DOL = contributing margin ratio/operating margin
Contributing margin ratio is the ratio of total revenue - total variable cost to total revenue. And operating margin is the ratio of operating income to total revenue. DOL is also the ratio of the change in operating income to the change in revenue.
As an example, if a company has a degree of leverage which is 1.5, this would mean a 15% increase in operating income for a 10% increase in sales revenue, but it also might indicate operating income falling by 15% for a 10% fall in revenue.
The degree of leverage is higher when fixed costs are higher and variable costs lower. This would be the case if production is automated by using advanced machinery. This is also the case when fixed expenditure on marketing, research, etc. is higher.
To ensure an appropriate operating income it is essential for companies to strike a right balance between the total costs and variable costs involved in creating what they sell.