NPV Net Present Value Calculator

Net present value: the gold standard of investment analysis

Net present value, abbreviated as NPV, is the most rigorous and theoretically sound method for evaluating capital investments. It calculates the difference between the present value of all future cash flows generated by an investment and the initial cost of that investment, expressed in today's dollars. A positive NPV means the investment creates value above its cost, accounting for the time value of money. A negative NPV means the investment destroys value. An NPV of zero means the investment exactly earns the required rate of return specified by the discount rate.

The time value of money is the core concept underlying NPV. A dollar received today is worth more than a dollar received in the future, because today's dollar can be invested to earn a return. The discount rate converts future cash flows into their equivalent value today. A cash flow of $25,000 received in year 3 discounted at 10 percent per year is worth $25,000 divided by (1.10 cubed), which equals $18,783 in today's terms. Summing these discounted values across all years of the investment's life gives the total present value of the investment's cash flows. Subtracting the initial investment gives the NPV.

For a uniform annual cash flow, the NPV calculation is equivalent to multiplying the annual cash flow by the present value annuity factor for the given discount rate and investment life, then subtracting the initial investment. If $25,000 per year for 7 years at 10 percent has an annuity factor of 4.868, the PV of cash flows is $121,700. Subtracting a $100,000 initial investment gives an NPV of $21,700. This positive NPV confirms the investment exceeds the 10 percent required return, creating $21,700 of value above the hurdle rate in today's dollars.

Choosing the right discount rate

The discount rate is the most subjective input in an NPV analysis and also the most consequential. For business investments, the discount rate typically represents the weighted average cost of capital (WACC), which is the blended cost of debt and equity funding used to finance the business. A business funded entirely by equity from owners expecting a 15 percent return would use 15 percent as its discount rate. A business with a mix of debt at 7 percent and equity at 12 percent would calculate a weighted average based on the proportions of each. For riskier investments, a higher discount rate is appropriate because the uncertainty of the cash flows justifies requiring a higher return to compensate for risk.

NPV vs IRR

NPV and internal rate of return (IRR) are the two most important capital budgeting tools. IRR is the discount rate that makes NPV exactly zero, and provides a percentage return for comparison against the required hurdle rate. For a single investment decision with conventional cash flows (an upfront cost followed by positive cash flows), NPV and IRR generally give consistent accept or reject signals. The key difference is that NPV expresses the value created in absolute dollar terms, while IRR expresses it as a percentage. When comparing mutually exclusive investments of different sizes, NPV is the more reliable guide because a higher percentage return on a smaller investment does not necessarily create more absolute value than a lower percentage return on a larger investment.

Profitability index

The profitability index divides the present value of future cash flows by the initial investment to give a ratio. A profitability index above 1.0 confirms a positive NPV investment. The profitability index is useful when comparing multiple projects competing for limited capital: a project with a PI of 1.35 on a $100,000 investment may be preferable to one with a PI of 1.20 on a $200,000 investment if the available capital is constrained, because the first creates more value per dollar invested. This capital rationing context is where the profitability index adds analytical value beyond simple NPV comparison.