What Is an IRR Calculator?
IRR (Internal Rate of Return) is the annualized rate of return that makes the net present value of a series of cash flows equal to zero. It's a core metric in capital budgeting for evaluating whether an investment or project is worthwhile.
How to Use the IRR Calculator
- Enter your initial investment (the upfront cash outflow).
- Add each year's expected cash inflow.
- The calculator solves for the IRR that balances these cash flows.
IRR Formula
Unlike most formulas, IRR has no direct algebraic solution — it's found by iteratively testing rates until the equation balances (this calculator does that automatically).
Worked Example
Initial investment: −$10,000
Cash inflows: $3,000 per year for 5 years
IRR: approximately 15.2%
Understanding Your Results
IRR represents the effective annualized return of the investment. A common rule of thumb: if IRR exceeds your required rate of return (or cost of capital), the investment is generally considered worthwhile.
IRR vs. ROI
ROI measures total return without regard to timing. IRR accounts for the timing of cash flows, recognizing that money received sooner is worth more than money received later — making it more useful for comparing investments with different cash flow schedules.
Common Mistakes to Avoid
- Comparing IRR across projects with very different scales or durations without additional context.
- Assuming a higher IRR is always better — very short-term, small investments can show high IRR without being the best overall use of capital.
- Not accounting for reinvestment assumptions, which IRR implicitly makes and which may not hold in practice.
Frequently Asked Questions
IRR measures the annualized rate of return of an investment based on its cash flow timing, used to evaluate and compare capital projects or investments.
ROI measures total return without regard to timing. IRR accounts for when cash flows occur, making it more useful for comparing investments with different timelines.
This depends on context and risk — many businesses compare IRR against their cost of capital or a required hurdle rate; there's no universal 'good' number.
Yes — a negative IRR means the investment loses money overall, since a negative discount rate would be needed to make the cash flows balance to zero.
Because it can require solving a polynomial equation with no simple algebraic solution, IRR is typically found through iterative approximation, which is what this calculator does automatically.