Days Receivable Outstanding (DRO) is a measuring tool used to track the average number of days that a business’ customers take to pay their debts. It is calculated by dividing the total accounts receivable from customers at a given point in time by the total sales for the same period, and then multiplying it by the amount of days in that billing period. DRO is an important figure for businesses, as a high DRO may indicate that customers aren’t paying their bills on time. By monitoring this statistic, companies can ensure that they have adequate cash flow to cover their operating costs.