Calculate internal rate of return for investment projects with irregular cash flows, MIRR comparison, and NPV profile charting.
A project schedule can contain an initial outlay, later receipts, and additional costs on their actual dates. This calculator solves for the annualized rate that makes those dated cash flows have zero net present value, compares that result with MIRR using separate finance and reinvestment assumptions, and shows how NPV changes across discount rates. The main trap is treating IRR as automatically unique: a schedule with more than one change in cash-flow sign can have multiple zero crossings or no useful IRR.
A concrete input and expected output from the current implementation.
Input
2025-01-01: -100 2026-01-01: 110
Expected output
IRR: 10.00%. The NPV profile crosses zero at 10.00%.
At a 10% annual discount rate, the later 110 is worth 110 / 1.10 = 100 on the first date. That exactly offsets the initial -100, so NPV is zero.
For a trial annual rate, each cash flow is discounted from its date back to the first date. IRR is any rate for which the sum of those discounted values is zero. Earlier and later payments therefore cannot be rearranged without changing the answer. The NPV profile makes the same relationship visible across a range of rates.
MIRR separates the cost of funding negative cash flows from the rate earned on positive cash flows. Negative amounts are valued using the finance rate, positive amounts are accumulated using the reinvestment rate, and the resulting endpoint values determine one annualized return for the project span. This can be easier to interpret when ordinary IRR has competing roots.
The IRR equation is a root-finding question, and its cash-flow pattern controls how many roots exist. With a conventional initial outflow followed only by inflows, there is normally one economically meaningful root. With later outflows, the NPV curve may cross zero repeatedly or never cross it. In those cases, no single IRR can summarize the schedule.
No. ROI is usually a simple gain relative to cost and often ignores timing. NPV is a currency amount calculated at a discount rate you choose. IRR is the rate at which NPV becomes zero. The measures can rank projects differently, especially when projects differ in size, timing, or duration.
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