IRR vs ROI: Why the Bigger Return Can Be the Worse Deal
A 30% gain over five years loses to a 20% gain over two. IRR is the number that shows it.
Quick answer: IRR is the annual rate that makes an investment's inflows and outflows balance to zero today. ROI tells you how much you gained; IRR tells you how fast. A 30% gain over five years is an IRR of about 5.4% a year. A 20% gain over two years is about 9.5%. IRR is the one that ranks deals correctly.
ROI is the number people quote at dinner. IRR is the number people use before signing. The difference between them is time, and time changes the ranking far more often than you would expect.
ROI says how much, IRR says how fast
ROI is gain divided by cost. Put in $50,000, get back $65,000, and your ROI is 30%. The formula neither knows nor cares whether that took five years or five months.
IRR asks a different question: what annual compounding rate turns your outflows into your inflows? For that same deal over five years, $50,000 becoming $65,000 works out at an IRR of about 5.4% a year.
Two deals, and the ranking flips
Deal A: $50,000 in, $65,000 back after five years. ROI 30%, IRR about 5.4%. Deal B: $50,000 in, $60,000 back after two years. ROI 20%, IRR about 9.5%.
By ROI, A wins by ten percentage points. By IRR, B wins by nearly double. B is the better deal for anyone who has somewhere to put the money during years three, four and five, which is almost everyone. It is the same effect that makes compound interest behave the way it does, applied to lumpy and irregular cash flows.
Run your own numbers
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Open the Irr CalculatorUneven cash flows, which is the real use case
Most things worth analysing do not pay out once at the end. A rental unit, a piece of equipment, a small business buyout: money leaves at the start and comes back in dribs over several years.
Take $10,000 out now, then $3,000 back at the end of each of the next four years. Total in, $12,000. Total out, $10,000. ROI says 20%. IRR says about 7.7% a year, and that is the honest figure, because the first $3,000 came back after twelve months and has been available to you ever since. ROI counts money you got back in year one as though it were still tied up in year four.
Where IRR quietly misleads
Three things to watch. First, IRR assumes every interim payment is reinvested at the IRR itself. If the calculated figure is 22% and your realistic alternative is 6%, the project's true performance sits somewhere below the headline. Second, IRR ignores scale: 40% on $5,000 is a smaller pile of money than 12% on $500,000, and a percentage will never tell you that. Third, if the cash flows change sign more than once, such as a project needing a second injection halfway through, there can be more than one mathematically valid IRR and the calculator will show you just one of them.
How to use the IRR calculator
Enter the initial investment as a negative number, because it is money leaving you, then each later cash flow in period order. Include zeros for periods with no payment, since it is the position in the sequence that carries the timing.
Include everything that is genuinely cash: purchase price, fees, repairs, rent received, and the sale proceeds at the end. Leave out non-cash items such as depreciation, which changes your tax bill but does not move money on the day. If you are running the numbers on a property, the rental analysis walk-through lists the inputs people most often forget to include.
Then read the result against a hurdle rate rather than in isolation. An IRR is only good relative to what else you could do with the same money, for the same length of time, at the same level of risk.
Common questions
What is a good IRR? Higher than your realistic alternative, with a margin for the extra risk and the lost liquidity. A 9% IRR on a small illiquid deal is unattractive if a liquid fund has done something similar over the same stretch. The number means nothing without the comparison.
Is IRR the same as annualised return? For a single sum in and a single sum out, yes, they give the same answer. They separate as soon as there are multiple cash flows at different times, which is precisely when IRR earns its keep.
Can IRR be negative? Yes. If your total inflows are worth less than your outflows, the IRR is negative and tells you the annual rate at which you lost money.
Why do IRR and NPV disagree about which project to pick? Usually because the projects differ in size or in lifespan. When the two conflict, NPV is generally the one to follow, because it answers in money rather than in a rate, and money is what you actually spend.