The deposit interest rate is the value that must be given by the bank to the customer in return for the current customer's deposit which will be returned by the bank at a later date. Deposit calculator as your investment simulation tool. Calculation calculator using formulas. Usually the deposit interest rate that applies is between 3% and 6% depending on the term of the deposit itself. The time periods to be used are 1 month, 3 months, 6 months and 12 months. List of available Bank Deposits