IRR & NPV Calculator
Is this investment worth it? Enter the initial investment, the cash flows you expect each year and a discount rate, and the calculator shows the NPV (net present value), the IRR (internal rate of return), the payback period and the ROI. These are the four numbers that tell you whether a project creates or destroys value.
Enter the initial investment, the discount rate you require (your cost of capital) and the net cash flow you expect each year. Use negative values for a year with a cash outflow.
How the result is reached
| Sum of cash flows | €15,000.00 |
| Net profit (cash flows minus investment) | €5,000.00 |
| Total ROI | 50% |
| Payback (recovery period) | 3.33 years |
| Decision | Creates value (positive NPV) |
Educational estimate, not financial advice. It assumes net, nominal yearly cash flows; it does not include taxes on profit, inflation or a residual value.
NPV: net present value
NPV brings every future cash flow back to today's value, at the discount rate you choose, and subtracts the initial investment: NPV = minus the investment, plus the sum of each cash flow divided by (1 + rate) to the power of the year. A euro received in five years is worth less than a euro today, and the discount rate measures that difference. If the NPV is positive the project creates value (it earns more than the required rate); if it is negative, it destroys value.
IRR: internal rate of return
The IRR is the discount rate that makes the NPV exactly zero: the project's implied annual return. The decision rule is simple, it is worth it when the IRR is above the discount rate (your cost of capital or required return). The calculator solves it numerically, finding the rate that zeroes the NPV.
Payback: how long to recover
The payback period is the number of years until the cumulative cash flows equal the investment. With 10,000 € invested and 3,000 € a year, it is recovered after 3 years and a third (3.3 years). It is the most intuitive number, but it ignores the time value of money and what happens afterwards, which is why it is used alongside NPV and IRR, not on its own.
ROI: total return
ROI (return on investment) is the total profit divided by the investment: ROI = (sum of cash flows minus the investment) divided by the investment. It measures how much you gained in total over the whole horizon, without spreading it across years. It is useful to compare the size of the gain, but it does not tell a 2-year return from a 10-year one; that is what the IRR (annual) and payback are for.
The discount rate is yours
The discount rate is what you enter as your cost of capital or minimum required return, it is not a legal value. Use the return of a safe alternative (a deposit or savings certificates) or the cost of your financing. The higher the rate, the more demanding the calculation and the lower the NPV.
Worked example
A 10,000 € investment that returns 3,000 € a year for 5 years, with a 5% discount rate. The cash flows sum to 15,000 €, so the total ROI is (15,000 minus 10,000) divided by 10,000 = 50%. Bringing each year's 3,000 € back to today at 5%, the NPV is 2,988 € (positive, the project creates value). The IRR, the rate that would zero the NPV, is about 15.2%, well above the 5% required, so the investment pays off. The simple payback is 3.3 years (the 10,000 € is recovered after three years and a third).
Frequently asked questions
What is NPV (net present value)?
What is IRR (internal rate of return)?
What is the difference between IRR and NPV?
What is payback?
Which discount rate should I use?
Does the calculator account for taxes and inflation?
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Sources
- Todos Contam: Portal de educação financeira — Banco de Portugal
- IAPMEI: apoio à gestão das pequenas e médias empresas — IAPMEI, Agência para a Competitividade e Inovação
Author: Thorben Rasmus Idel · Reviewed by: Nahar Geva · Last reviewed: 2026-06-25