Operating Expense Ratio Calculator

How it is calculated

The tool computes OER = operating expenses ÷ revenue × 100. Both inputs are money amounts for the same period (a month, a quarter or a year) and in the same currency; the result is a percentage shown to two decimals. Operating expenses must be zero or more and revenue must be greater than zero, otherwise there is no result. Ratios above 100% are allowed and simply mean the business spends more on operations than it earns. The tool divides exactly what you enter, so deciding what counts as an operating expense (rent, salaries, utilities, marketing) versus financing, tax or depreciation is up to you. Different industries and real estate segments define the numerator and revenue base slightly differently.

Common mistakes

• Mixing periods, such as annual expenses over monthly revenue. Both amounts must cover the same time span or the ratio is meaningless.
• Including interest, income tax or loan principal in operating expenses. Those sit below the operating line, and adding them inflates the ratio compared with peers.
• Using profit instead of revenue as the denominator. A ratio against profit can exceed 100% easily and does not describe cost efficiency.
• Forgetting to remove the cost of goods sold when comparing with a company that reports it separately. Whether COGS is inside operating expenses changes the ratio a lot, so compare like with like.
• Reading a high ratio as an error. The tool accepts values above 100%, and 120% is a valid loss-making result, not a typo.