To calculate bank interest on savings, use the formula for calculating the effect of compound interest on your bank balance. In this formula, “P” stands for the principal, “r” is the annual rate of interest, and n is the number of times the interest is compounded per year. The US central bank rate will, therefore, help determine the interest rate set on a savings account, and the methods outlined above regarding simple and compound interest explain how savings account interest is calculated. You can compare savings account interest rates offered by a range of banks using this online comparison tool. The difference goes to the profit of the bank. Both the Fed rate and LIBOR are short-term inter-bank interest rates, but the Fed rate is the main tool that the Federal Reserve uses to influence the supply of money in the U.S. economy. LIBOR is a commercial rate calculated from prevailing interest rates between highly credit-worthy institutions.