I have a friend who is an accountant and I personally would just ask him to do it for me, but since not all of us are this lucky then there are two ways I can share with you on how to calculate APY or Annual Percentage Yield. The easiest way is to use an Excel spread sheet. Paste this formula into a cell on the spreadsheet. =POWER((1+(A1/B1)),B1)-1 ,only you will need to replace the A1 with the interest rate and replace the B1 with the number of times it is compounded annually. The other way is to do it the old fashioned way. Remember A1 is the interest rate and B1 is the number of times it is compounded. Use the formula APY= 1+(A1/B1)to the power of B1 -1. See why I just ask my friend?