Formula Excel IRR

What this does

NPV discounts future cash flows back to today at a chosen rate and nets them against the upfront investment; a positive NPV means the project beats that rate. IRR is the discount rate at which NPV is exactly zero. The classic trap is that Excel's NPV assumes every value in its range sits one period in the future — so the year-0 investment must be added outside the function, while IRR wants the full series including year 0. The same idea underpins a lot of everyday Excel work, so the few minutes spent getting it right here pay back across every sheet you build afterwards. Treat it as a pattern, not a one-off, and it stops being something you look up and starts being something you reach for. For “formula excel irr”, the reliable version is a short checking loop, not just the first command that appears to work. Run it on a deliberately small range first, watch how the affected formula change, and only then apply the same setup to the full sheet. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. That is what makes a calculation you can defend to a CFO or an auditor useful in real work: repeatable, auditable, and not dependent on memory or luck.

A worked example

B1 holds -10000 (investment today), B2:B4 hold 3000, 4200, 6800. =NPV(10%,B2:B4)+B1 returns €1,307.29 — the project creates value at a 10% hurdle rate. =IRR(B1:B4) returns 16.36%, the rate at which the same series breaks even. NPV and IRR are the standard go/no-go arithmetic for investments, equipment purchases, and projects — and the off-by-one-period NPV trap is probably the most common spreadsheet finance error. Check the referenced cells, argument order and result type in your workbook. Start with the worked example before changing an input, then compare the changed result with the calculation you expected. An error value or a result of a different type is a reason to inspect the inputs and arguments.

In Google Sheets

Google Sheets support for this task has not been verified. Check the function, arguments and workflow in the target product before transferring the example. Matching formula notation does not establish identical behaviour. Nothing on this page is behind a login or a download: the exact answer is at the top, and the detail below it is there for when you need it. That is the whole promise here — the answer first, and just enough context to make it stick. For “formula excel irr”, keep the input cells and the result visible while you check the formula in Excel. Follow the worked example and change one input at a time. The steps explain the workbook calculation; this page does not run a live calculator for that task.

Common mistakes

• Including the year-0 investment inside the NPV range, which discounts it one year too many.
• Feeding IRR a series with no sign change — it needs at least one negative and one positive flow.
• Comparing projects of different lengths by IRR alone; NPV at a common rate is the safer ranking.
• Using annual NPV/IRR on monthly flows — switch the rate to a monthly rate or use XNPV/XIRR with real dates.

Frequently asked questions