Another component of cost-benefit analysis includes Quality-Adjusted Life Years (QALYs); the extra dollar cost of providing one additional year of life expectancy for evaluating health programs.

Equation:

where FV = future value,PV = present value

r = the interest rate

n = the number of time periods into the future

If you want instead to calculate how much money you would need today (present value) to achieve a particular future value (say $100 in five years), the equation can be rearranged:

PV = FV/(1 = r)ⁿ