NPV Calculator

How this calculator works

Net Present Value (NPV) is the gold standard for evaluating investment projects and capital budgeting decisions. It answers one question: is this investment worth more than it costs, after accounting for the time value of money? A positive NPV means the project creates value; a negative NPV means it destroys value. Most professional investors and corporate finance teams use NPV as their primary decision metric because it captures both the magnitude and timing of cash flows in a single dollar figure.

The principle behind NPV is that a dollar today is worth more than a dollar tomorrow — because today's dollar can be invested and earn returns. NPV discounts all future cash flows back to today's value using a discount rate (usually your cost of capital or required return), then subtracts the initial investment. The result is the net value created or destroyed in today's dollars. A $10,000 NPV means the investment creates $10,000 of value above your required return — not just breaks even, but creates value.

Enter your initial investment, expected annual cash flows for up to 7 years, and the discount rate. The calculator shows NPV, total undiscounted cash flow, and the present value of each year's cash flow. If NPV is positive, the investment clears your required return hurdle. If negative, you'd earn more by investing the money elsewhere at the discount rate. The year-by-year PV breakdown shows how much each future cash flow is worth in today's dollars — illuminating why distant cash flows contribute less than near ones.

The formula

Worked example

Methodology and sources

NPV implements the time value of money — the foundational principle of finance. A dollar today is worth more than a dollar tomorrow because it can be invested to earn returns. The discount rate reflects the opportunity cost of capital: the return you could earn on alternative investments of similar risk.

The discounting formula 1/(1+r)^t is mathematically the inverse of compound interest. Discounting future cash flows to present value is the mirror image of compounding present value to future value. Both rely on the same exponential math.

Choosing the right discount rate is critical. For personal investments, use your opportunity cost — what you'd earn elsewhere (e.g., 7-10% for stock market returns). For businesses, use the weighted average cost of capital (WACC), typically 8-12%. For riskier projects, add a risk premium to the discount rate. Higher discount rates make future cash flows worth less, making NPV more conservative.

Sources: Principles of Corporate Finance by Brealey, Myers, Allen; CFA Institute Corporate Finance curriculum; Harvard Business School capital budgeting methodology.

Industry benchmarks

Common discount rates by context:

• Personal investments (conservative): 5-7% (matching bond returns)
• Personal investments (market average): 7-10% (matching stock returns)
• Small business projects: 12-20% (higher risk premium)
• Established business projects: 8-12% (WACC)
• Real estate development: 10-15%
• Startup investments: 30-50%+ (very high risk)
• Government projects: 3-7% (low risk, social discount rate)

Higher discount rates favor short-term payoffs; lower rates favor long-term projects. This is why tech companies with low WACC invest in long-horizon R&D, while small businesses with high WACC focus on quick payback.

Common mistakes to avoid

Mistake 1: Using too low a discount rate. This overvalues distant cash flows and makes marginal projects look attractive. If your project is risky, use a higher rate. Better to be conservative.

Mistake 2: Forgetting to include working capital and capex. Many projects require ongoing investment in inventory, receivables, and equipment. Include these as negative cash flows in the years they occur.

Mistake 3: Overstating cash flow projections. Optimism bias is real. Use conservative estimates, especially for revenue. Many projects fail to meet projections — the discount rate can't fix unrealistic inputs.

Mistake 4: Ignoring terminal value. For businesses with value beyond the forecast period, include a terminal value (often based on selling the business or perpetuity assumption). Excluding it understates project value.

Mistake 5: Using NPV for mutually exclusive projects of different sizes. NPV measures total value created, not efficiency. A $1M project with $200K NPV creates more value than a $100K project with $50K NPV, but the smaller project is more efficient. Use profitability index for ranking.

When to use this calculator

Use NPV for any capital budgeting decision: equipment purchases, expansion projects, acquisitions, R&D investments, real estate, and business valuations. NPV is the most theoretically sound investment metric — it measures dollar value created, accounts for time value, and accepts any pattern of cash flows.

For choosing between mutually exclusive projects, NPV works well when projects are similar in size and duration. For projects of very different sizes, also compute profitability index (PI = PV/Investment). For projects of different durations, use equivalent annual annuity (EAA) to normalize.

For business valuation, NPV is the foundation of discounted cash flow (DCF) analysis — the standard valuation method used by investment bankers, private equity, and corporate development teams.

Related metrics and alternatives

IRR (Internal Rate of Return): The discount rate that makes NPV = 0. Measures percentage return. Useful for comparing to a hurdle rate but can mislead on mutually exclusive projects.

Payback period: Time to recover initial investment. Simple but ignores time value and cash flows after payback.

Profitability index (PI): PV of cash flows / initial investment. Useful for ranking projects of different sizes. PI > 1.0 = positive NPV.

Modified IRR (MIRR): Addresses IRR's reinvestment rate assumption by using a specified reinvestment rate. More realistic for comparison.

Discounted payback period: Payback period using discounted cash flows. More accurate than simple payback.

How to interpret the results

NPV > 0: Investment creates value above the required return. Accept the project.

NPV = 0: Investment earns exactly the required return. Indifferent — accept or reject based on other factors.

NPV < 0: Investment destroys value. Reject — you'd earn more by investing at the discount rate elsewhere.

NPV highly sensitive to discount rate: Project has most of its value in distant cash flows. Riskier than it appears — small changes in assumptions swing NPV dramatically.

NPV insensitive to discount rate: Project has most value in near-term cash flows. Lower risk — predictions are more reliable for the near future.