IRR Calculator

The Internal Rate of Return is the discount rate at which the Net Present Value of all cash flows equals exactly zero. Unlike simpler return measures such as ROI or payback period, IRR accounts for the time value of money — a dollar received today is worth more than a dollar received five years from now. The calculation uses an iterative numerical method (often bisection or Newton–Raphson) because there is no closed-form algebraic solution. You provide an initial investment (entered as a negative number) and a series of future inflows. The calculator then searches for the rate that balances the discounted inflows against the outflow. In practice, an IRR of 18% means the investment compounds at 18% per year on the unrecovered capital balance — equivalent to earning 18% annually in a bank account on the outstanding balance. This annualized perspective makes IRR intuitive for comparing across asset classes, from real estate development to private equity to corporate capital budgeting. Always interpret IRR alongside NPV, not as a standalone figure, because two projects can share the same IRR but create very different amounts of absolute value.

Standard IRR carries a hidden assumption that all positive cash flows are reinvested at the IRR itself. When IRR is high — say, 35% — this assumption implies you can redeploy every dollar of cash flow at a 35% return, which is rarely realistic. Modified IRR (MIRR) corrects this by letting you specify two separate rates: a finance rate for discounting negative cash flows (your cost of capital) and a reinvestment rate for compounding positive cash flows (what you can realistically earn elsewhere). The result is almost always lower than IRR but more reliable. For example, a project with an IRR of 35% might have a MIRR of only 22% when reinvestment is capped at 8%. MIRR also solves another IRR weakness: when cash flows change sign more than once, standard IRR can produce multiple valid solutions. MIRR always returns a unique answer. For serious investment analysis, report both metrics — IRR for comparability with benchmarks and MIRR for practical decision-making accuracy.

IRR tells you the rate of return; NPV tells you the dollar value created. A $500,000 project returning 40% IRR creates far less wealth than a $10 million project returning 15% IRR if your cost of capital is 10%. This is the scale problem with IRR: it favors small, high-percentage projects over larger, high-value ones. NPV avoids this by measuring absolute dollar value at your specific hurdle rate. The Profitability Index (PI = PV of inflows / initial investment) bridges the two by expressing NPV per dollar invested, which is useful when you face capital constraints and need to rank competing projects. A PI above 1.0 means the project creates value; below 1.0 it destroys value. When evaluating a project, review all three: IRR for comparability, NPV for value created, and PI for capital efficiency. This calculator computes all three simultaneously alongside MOIC and payback period so you can make fully informed decisions without switching between tools.

The most common mistake is accepting any project with IRR above the hurdle rate without checking scale. As described above, a 25% IRR on a $50,000 project is usually less valuable than a 15% IRR on a $1 million project at a 10% cost of capital. A second mistake is ignoring multiple IRR solutions. When cash flows switch from positive to negative more than once — for example, a mining project with a large reclamation cost in the final year — the IRR equation may have two or more valid solutions. Standard IRR calculators return only one, often without warning. MIRR is the correct tool in this situation. A third mistake is using IRR to compare projects with very different durations. A five-year project with 20% IRR is not directly comparable to a two-year project with 20% IRR, because you must also consider what you do with the capital after the shorter project ends. Always model the full investment horizon when making capital allocation decisions using this calculator's scenario comparison features.

The NPV Profile chart plots NPV on the vertical axis against discount rate on the horizontal axis. The curve crosses zero at the IRR — this crossing point is the visual definition of IRR. To the left of the crossing (lower discount rates), NPV is positive and the project creates value. To the right (higher discount rates), NPV is negative and the project destroys value. The gold vertical line marks the IRR; the indigo line marks your hurdle rate. The gap between these lines is your margin of safety — the wider the gap, the more buffer you have if your actual cost of capital rises or cash flows disappoint. A steep NPV curve (dropping sharply as the discount rate rises) indicates a project that is highly sensitive to the discount rate assumption. A flat curve means the IRR and NPV conclusions are robust even if your cost of capital estimate is somewhat off. Use this visual to quickly assess the risk profile of each investment scenario before committing capital.