This simple equation is what drives our future value calculator as well. Financial caution. This is an online future value calculator which is a good starting point in estimating the future value of an investment and the capital growth you can expect from a bank deposit or a similar investment, but is by no means the end of such a process. To calculate future value with simple interest, you can use the mathematical formula FV = P times the sum of 1 + rt. In this formula, FV is future value, and is the variable you’re solving for. P is the principal amount, r is the rate of interest per year, expressed as a decimal, and t is the number of years in the equation. Future value is the value of a sum of cash to be paid on a specific date in the future. An ordinary annuity is a series of payments made at the end of each period in the series. Therefore, the formula for the future value of an ordinary annuity refers to the value on a specific future date of a series of periodic payments, where each payment is