NPV Calculator

The core logic of NPV rests on the time value of money: a dollar in hand today is worth more than a dollar promised in the future because you can invest it now and earn a return. If your cost of capital is 8%, then $100 received one year from now is worth only about $92.59 today — you would be indifferent between receiving $92.59 now and $100 in 12 months. The NPV formula formalizes this intuition by discounting every future cash flow back to the present using your required rate of return. When you sum those discounted values and subtract the initial outlay, the result tells you — in today's dollars — how much wealth the project creates. A positive NPV means the project earns more than your cost of capital; a negative NPV means it destroys wealth relative to your alternative uses of the same money. This is why positive-NPV decisions are always the correct financial choice in theory, and why it is the standard method used by finance professionals worldwide.

The discount rate is the most consequential input in an NPV calculation, and choosing it incorrectly can flip a project from accept to reject. For businesses, the most defensible choice is the weighted average cost of capital (WACC) — a blend of the cost of equity and after-tax cost of debt, weighted by each source's share of total financing. WACC for mid-cap companies typically falls between 8% and 12%. For individual investors, the discount rate should reflect the return you could realistically earn on an alternative investment of comparable risk — often 7–10% for equity-like projects. A risk-free comparison uses the current 10-year Treasury yield. If you are unsure, run the calculation at multiple rates (say 7%, 10%, and 13%) to see how sensitive the NPV is to your assumption. Projects with a strongly positive NPV at 13% are robustly attractive; projects that only work at 7% deserve more scrutiny before commitment.

NPV and Internal Rate of Return (IRR) are complementary tools that usually tell the same story. When a project's IRR exceeds the discount rate, its NPV is positive — both methods say accept. The conflict arises when comparing two mutually exclusive projects: the one with the higher IRR is not always the one with the higher NPV. A smaller project may have an IRR of 25% but generate only $10,000 of NPV, while a larger project at 15% IRR might generate $80,000 of NPV. If you can only choose one, maximize NPV — it represents actual dollars added to your wealth. IRR is also unreliable for non-conventional cash flow patterns (projects with multiple sign changes), where it may produce multiple valid solutions. Use IRR as a quick filter and a communication tool, but always base the final decision on NPV. The NPV Curve chart in this calculator shows exactly where NPV crosses zero — that crossing point is the IRR.

NPV has two well-known limitations in practice. First, it requires accurate cash flow forecasts — garbage in, garbage out. For projects beyond 3–5 years, cash flow uncertainty grows substantially, which is why many analysts apply progressively higher discount rates to later periods or use dedicated scenario analysis rather than a single point estimate. Second, NPV ignores option value: the ability to expand, delay, or abandon a project in response to new information. Real options analysis extends NPV by valuing this flexibility, but it requires significantly more inputs and financial modeling expertise. For most capital budgeting decisions, the practical solution is to run three scenarios — conservative (cash flows 20% below forecast), base, and optimistic (20% above) — and only commit to projects that show positive NPV even under the conservative case. A project that only works under rosy assumptions is carrying hidden risk. This calculator's Scenario Analysis tab automates this three-scenario comparison so you can immediately see how sensitive your decision is to forecast error before putting capital at risk.