An annuity is a financial product that pays out in equal intervals over time, such as but not limited to a retirement fund. This calculator assists in working out the present value of annuity based on the known future value and interest rate applied. This present value of annuity calculator works oppositely to the future value of annuity calculator which takes the known current value, known interest rate and known number of periods to then accumulate to the future value. The present value is calculated by reducing a value over time from the endpoint by the specific interest rate per period to reach the current value. The key to both of these calculations in the interest rate which is the main compounding factor.