IRR should not be used as a standalone metric when evaluating projects with non-conventional cash flows (multiple sign changes), mutually exclusive projects of different scales or durations, or when comparing projects with significantly different risk profiles. It overestimates returns by assuming reinvestment at the high IRR rate, rather than the cost of capital.
IRR can sometimes give me a misleading picture about whether or not the project is adding value to the firm when cash flows reverse from positive to negative during a project. In a situation where money comes in and then money goes out, the sign, negative and positive, flips.
Internal Rate of Return (IRR) is widely used in venture capital to measure annualized profitability, but it has critical flaws that can mislead investors. Key limitations include sensitivity to cash flow timing, unrealistic reinvestment assumptions, and its inability to reflect absolute dollar returns.
IRR works only for investments that have an initial cash outflow (the purchase of the investment) followed by one or more cash inflows. IRR can't be used if the investment generates interim negative cash flows. IRR does not measure the absolute size of the investment or the return.
With mutually exclusive projects, IRR can be misleading. IRR sometimes ignores magnitude of scale of the project. IRR is also unreliable in ranking projects that offer different patterns of cash flows over time.
If IRR > Cost of Capital → The project adds value and should be accepted. If IRR < Cost of Capital → The project destroys value and should be rejected.
Disadvantages of IRR
Unlike net present value, the internal rate of return doesn't give you the return on the initial investment in terms of real dollars. For example, knowing an IRR of 30% alone doesn't tell you if it's 30% of $10,000 or 30% of $1,000,000.
Because of the nature of the formula, however, IRR cannot be calculated analytically and must instead be calculated either through trial-and-error or using software programmed to calculate IRR. Generally speaking, the higher a project's internal rate of return, the more desirable it is to undertake.
So the rule of thumb is that, for “double your money” scenarios, you take 100%, divide by the # of years, and then estimate the IRR as about 75-80% of that value. For example, if you double your money in 3 years, 100% / 3 = 33%. 75% of 33% is about 25%, which is the approximate IRR in this case.
If a project has alternating positive and negative cash flows, multiple IRR values may result, leading to confusion and difficulty in decision making. In contrast, NPV will always provide a unique, consistent result, making it a more reliable method in these cases.
What is a good IRR? In general, a higher IRR indicates higher profitability. If the IRR is less than the cost of capital, the investment may not be feasible. It's also important to consider how the IRR stacks up against other potential investment opportunities' IRRs.
ROI indicates total growth, start to finish, of an investment, while IRR identifies the annual growth rate. ROI is more common than IRR, as IRR tends to be more difficult to calculate—although software has made calculating IRR easier.
Private equity firms generally target annual IRRs between 20% and 30% or higher. This target compensates for the illiquidity, longer holding periods, and hands-on operational involvement characteristic of PE investments.
The IRR decision rule should be avoided in situations involving multiple rates of return, selection of mutually exclusive projects, and project NPV not declining smoothly.
Erroneously imposed on NPV and IRR, this fallacy suggests that already-distributed cash flows must be reinvested at an assumed rate. This is logically flawed: once cash flows incorporate the firm's reinvestment and payout policies, no further assumptions are needed. Adding them implies distorting true profitability.
The "7-3-2 Rule" refers to two main concepts: a financial strategy for wealth building, suggesting it takes 7 years for the first major savings milestone, 3 years for the next, and 2 years for the third, driven by compounding and increasing investments; and a trucking rule (7/3 split) allowing drivers to split their 10-hour mandatory break into 7 hours in the sleeper berth and 3 hours of off-duty rest, offering flexibility.
The "7% rule" in real estate typically refers to a quick screening tool where an investor checks if a rental property's gross annual rent is at least 7% of its purchase price, indicating a potentially solid income investment, though it's not a substitute for detailed analysis; however, other "7 rules" exist, like those focusing on agent performance (top 7% of agents do most business) or key investment principles (due diligence, diversification, market awareness, clear strategy) for long-term success.
Limitations of IRR
In the case of positive cash flows followed by negative ones and then by positive ones, the IRR may have multiple values. Moreover, if all cash flows have the same sign (i.e., the project never turns a profit), then no discount rate will produce a zero NPV.
If the IRR is greater than a pre-set percentage target, the project is accepted. If the IRR is less than the target, the project is rejected. Considering the definition leads us to the calculation. The IRR uses cash flows (not profits) and more specifically, relevant cash flows for a project.
"12% IRR" means the Internal Rate of Return for an investment is 12%, indicating it's expected to yield an average annual return of 12%, making all future positive cash flows equal in present value to the initial investment, essentially representing the compound growth rate of the investment. It's a key metric for deciding if an investment is profitable, with a 12% IRR suggesting the project breaks even (Net Present Value is zero) at that rate, so it's attractive if your required return is below 12% and less so if it's higher.
The IRR doesn't consider the project's actual dollar value or irregular cash flows. If there are any irregular or uncommon forms of cash flow, the rule shouldn't be applied. If it is, it may result in flawed findings.
Understanding IRR helps investors and business owners evaluate the profitability of investments over a five-year horizon. A good IRR typically exceeds your cost of capital, indicating value creation. High-growth investments often target IRRs between 20% and 30%, depending on risk.
The choice depends on the use. IRR is useful when comparing multiple projects against each other. It also is more appropriate when it is difficult to determine a discount rate. NPV is better in situations where there are varying directions of cash flow over time or multiple discount rates.