What is NPV (Net Present Value) in investing?
NPV (Net Present Value) answers a simple but fundamental question: does this investment create more value than putting that money to work at my chosen benchmark rate? If NPV is positive, the investment outperforms the alternative. If negative, you're destroying value relative to what you could earn elsewhere. It's the most rigorous single number in investment analysis.
- Positive NPV: investment creates value above your benchmark rate
- Negative NPV: the investment destroys value and the alternative would be better
- Discount rate = your opportunity cost: mortgage rate, bond yield, or index fund return
- NPV > 0 and IRR > discount rate always go together
- NPV in €, IRR in %: use both for a complete picture
- Always run the pessimistic and optimistic cases: if NPV stays positive when things go wrong, the margin of safety is real
The logic behind NPV: money has a time value
€100 today is worth more than €100 in 10 years, because today's €100 can be invested and earn returns. NPV discounts all future cash flows from an investment back to their present-day equivalent using a discount rate: your opportunity cost, or what you would earn in a comparable alternative. It then sums all those present values and subtracts the initial investment. The result is the additional value the investment creates above your benchmark.
How to interpret NPV
Positive NPV: the investment creates more value than putting the money at your chosen discount rate, and the bigger the figure the better. Zero NPV: it comes out exactly level with the alternative, so there is nothing to choose between them. Negative NPV: the investment destroys value relative to your benchmark. You'd be financially better off with the alternative.
How to choose the right discount rate
The discount rate is the most important input, and the most subjective. Common choices: your mortgage interest rate (if the property earns more than the loan costs you, NPV is positive); the 10-year government bond yield (the risk-free minimum hurdle); or the long-run average return of a global index fund (5–7% real). The higher your discount rate, the more demanding the hurdle. A rate that's too low will make bad investments look acceptable; too high will reject reasonable ones.
Step-by-step example
You invest €150,000, collect €7,500/year net rent for 10 years, and sell for €180,000. At a 5% discount rate (your opportunity cost), NPV ≈ +€24,000. This means that even if you could earn 5% per year elsewhere, this property still generates an additional €24,000 of value in today's terms. If you set the discount rate at 8%, NPV might turn negative, meaning that at that hurdle the investment does not justify its risk.
NPV vs. IRR: complementary tools
NPV and IRR analyze the same investment from different angles. IRR is the annualized return of the investment as a percentage. NPV tells you how much additional value (in today's euros) the investment creates above your benchmark rate. They always agree in direction: when IRR > discount rate, NPV > 0. When IRR < discount rate, NPV < 0. The advantage of NPV over IRR is that it measures value in absolute terms: an investment with an NPV of €40,000 creates more total value than one with NPV €20,000, even if the second has a higher IRR.
Limitations and how to use NPV in practice
NPV depends on estimated future cash flows (rent and sale price) and on a discount rate you choose yourself, so a small change in either can flip the sign of the result. Run three scenarios: base case, pessimistic (lower rent, lower exit price) and optimistic (higher rent, faster appreciation). If NPV is positive even under the pessimistic scenario, the investment has a strong safety margin. If NPV only turns positive in the optimistic case, you're relying on everything going right.
Frequently asked questions
What is NPV?
The value today of all future cash flows of an investment, discounted at a required rate, minus the initial cost.
What does a positive NPV mean?
The investment returns more than your required rate, so it creates value.
Which discount rate should I use?
Your opportunity cost: the return you could get from an alternative with similar risk.
NPV or IRR?
Use both. NPV shows value in money; IRR shows the return as a percentage.