The Internal Rate of Return (IRR) is the annualized effective compounded rate of return that makes the Net Present Value (NPV) of all cash flows (both positive and negative) exactly zero. It is the break-even interest rate used by investors to measure the profitability of potential investments. [ 1 , 2 ] How it Works The "If-Then" Test: If an investment's IRR is 15%, it means the project is expected to grow your invested capital at a compound annual rate of 15%. Comparison to Hurdle Rate: Investors compare the IRR to their "hurdle rate" or cost of capital. If the IRR exceeds this target, the project is generally accepted. Ranking Investments: When choosing between multiple projects, investors typically prefer the one with the highest IRR, assuming the risks are comparable. [ 1 ] The Mathematical Formula IRR is the discount rate (r) that satisfies the following formula, where $C_t$ represents the cash flow at time t, C₀ is the initial investment, and N is ...