The true annual return on a project.

What Is Internal Rate of Return (IRR)?

The Internal Rate of Return (IRR) is the discount rate at which the net present value (NPV) of all cash flows from an investment equals zero. In simpler terms, it represents the annualized rate of return an investment is expected to generate over its lifetime. IRR is widely used in corporate finance and private equity to evaluate the attractiveness of projects, acquisitions, and capital investments. An investment is generally considered worthwhile when its IRR exceeds the company's required rate of return or cost of capital, often called the hurdle rate.

IRR vs NPV: Which Should You Use?

While both IRR and NPV are discounted cash flow methods used to evaluate investments, they can occasionally lead to different conclusions. NPV calculates the dollar value an investment adds to the firm using a specified discount rate, making it straightforward to interpret, a positive NPV means the project creates value. IRR expresses returns as a percentage, which makes it intuitive for comparing projects of different sizes but can be misleading when cash flow patterns are unconventional. Most financial experts recommend using NPV as the primary decision tool and IRR as a complementary metric, since NPV directly measures value creation while IRR can produce multiple or misleading results in certain scenarios.

How to Interpret Your IRR Result

Interpreting IRR starts with comparing it to your minimum acceptable return, which is typically your weighted average cost of capital (WACC) or an opportunity cost benchmark. If a project's IRR is 15% and your hurdle rate is 10%, the project generates returns above your minimum threshold and may be worth pursuing. When comparing multiple investments, the one with the higher IRR is not always the better choice, a project with a lower IRR but larger NPV may create more total wealth. Context matters as well: a 20% IRR on a one-year project is very different from a 20% IRR on a ten-year project in terms of total value generated.

Limitations of IRR in Investment Analysis

IRR has several well-known limitations that investors and analysts should understand. It assumes that all interim cash flows are reinvested at the IRR itself, which is often unrealistic for projects with very high returns. Projects with alternating positive and negative cash flows can produce multiple IRRs, making interpretation ambiguous. IRR also ignores the scale of investment, a 50% return on a $1,000 investment creates far less wealth than a 15% return on a $1 million investment. The Modified Internal Rate of Return (MIRR) addresses some of these issues by assuming reinvestment at a more realistic rate, such as the cost of capital.