List the cash flows of an investment, one per period: the money you put in as a negative number, then what comes back each year. The calculator gives the internal rate of return, the net present value at your discount rate and how long it takes to pay back.
Internal rate of return (IRR)
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NPV = Σ CFk ÷ (1 + r)k
The IRR is the discount rate at which the NPV is exactly zero — the yearly return the investment earns. If the IRR is above the return you require, the project is worth doing; a positive NPV at your required rate says the same thing in money.
Separate the values with commas, spaces or new lines. Periods are usually years, but they can be months — then the IRR is a monthly rate.
ROI compares total gain with the money invested and ignores timing. IRR accounts for when each amount arrives, so money returned sooner counts for more.
If cash flows change sign several times (negative, positive, negative again), more than one rate can give an NPV of zero. In that case rely on the NPV at your own discount rate.