The cost-to-income ratio is a key financial measure, particularly important in valuing banks. It shows a company’s costs in relation to its income. To get the ratio, divide the operating costs (administrative and fixed costs, such as salaries and property expenses, but not bad debts that have been written off) by operating income. The ratio gives investors a clear view of how efficiently the firm is being run – the lower it is, the more profitable the bank will be. Changes in the ratio can also highlight potential problems: if the ratio rises from one period to the next, it means that costs are rising at a higher rate than income, which could suggest that the company has taken its eye off the ball in the drive to attract more business.