The operating ratio is a financial term defined as a company's operating expenses as a percentage of revenue. This financial ratio

Financial ratio

A financial ratio is a relative magnitude of two selected numerical values taken from an enterprise's financial statements. Often used in accounting, there are many standard ratios used to try to evaluate the overall financial condition of a corporation or other organization...

 is most commonly used for industries which require a large percentage of revenues to maintain operations, such as railroads. In railroading, an operating ratio of 80 or lower is considered desirable.