The Compound Interest Calculator is for calculating how much the balance in a savings or investment account might grow over time. You enter the amount you already have (or plan to deposit) in the account. Then enter the interest rate or investment performance rate, along with how long you plan to leave the money in the account. The compound frequency will vary from one bank or investment fund to another. The last two fields is where you enter the amount you plan to deposit on a recurring basis in the future.
The Return on Investment (ROI) Calculator is more basic. Use this calculator to compute the percentage by which your money grew in your savings or investment account. Enter the amount deposited or invested when you opened the account. The enter its balance now. When you click Submit, the calculator will compute your ROI percentage.