An operating expense, operating expenditure, operational expense, operational expenditure or OPEX is an ongoing cost for running a product, business, or system. Its counterpart, a capital expenditure (CAPEX), is the cost of developing or providing non-consumable parts for the product or system. For example, the purchase of a photocopier involves CAPEX, and the annual paper, toner, power and maintenance costs represents OPEX. For larger systems like businesses, OPEX may also include the cost of workers and facility expenses such as rent and utilities.

In business, an operating expense is a day-to-day expense such as sales and administration, or research & development, as opposed to production, costs, and pricing. In short, this is the money the business spends in order to turn inventory into throughput.

On an income statement, “operating expenses” is the sum of a business’s operating expenses for a period of time, such as a month or year.