NPV Calculator

What Is Net Present Value (NPV)?

Net Present Value (NPV) is the cornerstone of discounted cash flow (DCF) analysis. It calculates the present-day value of all future cash flows generated by an investment, discounted at a required rate of return, minus the initial outlay. A positive NPV means the investment creates value above the required return.

The Internal Rate of Return (IRR) is the discount rate that makes NPV equal to zero — it represents the project's effective annual return. The Profitability Index (PI) equals the present value of future cash flows divided by the initial investment; PI > 1 indicates a worthwhile project.

NPV is preferred over simpler metrics because it accounts for the time value of money: a dollar received today is worth more than a dollar received in the future due to earning potential, inflation, and risk.

Formula: NPV = −I₀ + Σ CFₜ / (1 + r)ᵗ for t = 1..n IRR: solve NPV = 0 for r PI = (NPV + I₀) / I₀

Example Calculation

Initial investment = $100,000. Cash flows: Year 1 = $30,000, Year 2 = $40,000, Year 3 = $50,000. Discount rate = 10%. NPV = −100,000 + 30,000/1.1 + 40,000/1.21 + 50,000/1.331 = −100,000 + 27,273 + 33,058 + 37,566 = −$2,103 (negative, project destroys value at 10%).

When to Use This Calculator

• A financial analyst evaluating a capital investment project by discounting projected cash flows to determine if it creates shareholder value
• A startup founder comparing multiple business opportunities by computing NPV and IRR for each to guide resource allocation
• A corporate finance team prioritizing a portfolio of projects using Profitability Index when capital budgets are constrained
• A real estate investor analyzing rental property acquisitions based on projected rental income streams

Common Mistakes to Avoid

• Using a discount rate that does not match the project risk — a risky venture should use a higher rate than a low-risk government contract; the rate should reflect both the cost of capital and the specific risk profile
• Forgetting to include the initial investment as a negative cash flow in year 0 — omitting it inflates NPV and makes every project look profitable
• Treating cash flow projections as certain — NPV is only as reliable as the cash flow estimates; perform sensitivity analysis on key assumptions to understand the range of possible outcomes
• Comparing IRR of projects with different scales — a small project with 50% IRR creates less value than a large project with 20% IRR; use NPV for absolute value comparison

How to Interpret Results

• NPV > 0 means the investment creates value above the required return — accept the project if NPV is positive
• IRR > discount rate confirms the project exceeds the hurdle rate; the higher the margin, the more cushion against estimation errors
• If NPV is negative but close to zero, a small improvement in cash flows or a slightly lower discount rate could make the project viable — investigate whether assumptions can be improved

Related Standards & References

• Fisher, I. (1930), The Theory of Interest — theoretical foundation of present value and the time value of money
• Brealey, Myers & Allen, Principles of Corporate Finance (McGraw-Hill) — standard reference for NPV, IRR, and profitability index decision rules
• US OMB Circular A-94 — prescribed discount rates and discounted-cash-flow methodology for US federal benefit-cost analysis

Frequently Asked Questions

What discount rate should I use for NPV?

Use your weighted average cost of capital (WACC) for corporate projects, or your personal required rate of return for individual investments. Common ranges: 8-12% for established businesses, 15-25% for startups or high-risk ventures. The rate should reflect the opportunity cost and risk of the specific investment.

What if NPV and IRR give conflicting rankings?

This can happen with mutually exclusive projects of different scales or timing. NPV is generally preferred because it measures absolute value creation in dollars, while IRR can be misleading with non-conventional cash flows (multiple sign changes) or when comparing projects of very different sizes.

What does a Profitability Index greater than 1 mean?

PI > 1 means the present value of future cash flows exceeds the initial investment — the project creates value. PI = 1.25 means every dollar invested returns $1.25 in present value. PI is especially useful for ranking projects when capital is limited, as it measures value per dollar invested.