The internal rate of return (IRR) is the annualized rate of return hidden inside a stream of cash flows. Given an upfront cost and a series of future payouts, IRR is the single discount rate that makes the present value of those payouts exactly equal to what you paid. It answers the question every investor, CFO, and real-estate buyer actually asks: "If I put this money in today, what am I really earning per year?"
This calculator solves IRR for up to five years of project cash flows and then compares the result against your hurdle rate — the minimum annual return you demand to take the risk. Enter the initial investment as a positive cost, type in each year's net cash flow, and read the implied annual return. Unlike a simple "total profit" number, IRR accounts for the timing of money: a dollar you get next year is worth more than a dollar you get in year five.
How to Use
- Enter the Initial Investment (at Time 0) — the upfront cost today, as a positive number (for example 100000 for a $100,000 outlay). The engine automatically treats this as the t=0 outflow.
- Type your expected net Cash Flow — Year 1, Year 2, and so on through Year 5. Enter inflows as positive numbers and any extra costs (maintenance, buyouts) as negatives.
- If the project ends in year five with a residual value — the sale of equipment, a building, or a book of business — fold that salvage value into Year 5.
- Set your Hurdle Rate (your required annual return, often your weighted average cost of capital or a market benchmark like a broad index fund's long-run return).
- Read the result card. The highlighted IRR is the implied annualized return. The Vs. Hurdle Rate line tells you PASS (IRR clears your bar) or FAIL (it does not).
- Use the supporting numbers — total undiscounted profit, net cash flow at a 0% discount, and the simple payback period — to sanity-check whether the IRR story matches your gut.
A project with an IRR of 15% is not "15% per year in your pocket" in the way a savings account is. It is the constant annual rate that discounts every future cash flow back to today's cost. It is the right number to compare against another project, a loan rate, or your benchmark.
The IRR Formula
IRR is the discount rate r that solves:
NPV(r) = −I₀ + Σ CFₜ / (1 + r)ᵗ = 0
Where:
- I₀ is the initial investment (the upfront outflow at time 0).
- CFₜ is the net cash flow at the end of year
t. - r is the internal rate of return, expressed as an annual decimal.
There is no closed-form algebraic solution for r once you have more than a couple of cash flows. The engine solves the equation numerically, the same way Excel's IRR() and Google Sheets' IRR() functions do: it bisects the discount rate between −99% and +1000% until the net present value lands on zero to within a fraction of a cent. This is the same root-finding approach used by the open-source numpy-financial library.
Worked example: invest $100,000 today, receive $25,000 at the end of each of the next five years. The cash-flow stream is −100,000, +25,000, +25,000, +25,000, +25,000, +25,000. Solving NPV = 0 gives an IRR of about 7.93%. That means the project is equivalent to putting $100,000 in an account that pays a steady 7.93% per year for five years and then closes. If your hurdle rate is 10%, the project fails — you would rather earn 10% elsewhere.
If the sum of all undiscounted cash flows exactly equals the initial investment, the IRR collapses to 0%: you get your money back but earn nothing on it. That is the breakeven line, and it is the most important sanity check on any IRR number.
IRR vs NPV: They Are Not the Same
This is the single most common confusion around this tool. NPV (net present value) is a dollar figure: at a chosen discount rate, it tells you how much value the project creates in today's dollars. IRR is a percentage: it is the implied discount rate at which that NPV would equal zero. They are two sides of the same equation, but they answer different questions:
- NPV answers: "At my required return of 10%, is this deal worth doing?" (Yes if NPV > $0.)
- IRR answers: "What return am I actually getting, regardless of my discount assumption?"
Use IRR to rank projects of similar size against each other or against a known benchmark (a mortgage rate, a bond yield, an index-fund expected return). Use NPV when you have a specific hurdle rate and need a dollar-value decision. This calculator reports IRR as the headline number and shows the undiscounted net cash flow as a reference line — but it deliberately does not present an NPV in dollars, because NPV depends on the discount rate you choose, whereas IRR is determined entirely by the cash flows themselves.
When IRR Lies
IRR is powerful, but it has three well-known failure modes that every user should know before trusting a result:
- No sign change, no solution. If every cash flow is positive (you never spend anything) or every cash flow is negative, there is no discount rate that makes NPV zero. The engine rejects this case with an error rather than returning a nonsense rate.
- Multiple IRRs. If cash flows flip sign more than once (say, an outflow, then inflows, then a large cleanup cost at the end), the NPV curve can cross zero more than once. Bisection returns one of the roots, but no single IRR is "the" answer — use the modified internal rate of return (MIRR) instead.
- Reinvestment assumption. IRR implicitly assumes every intermediate cash flow gets reinvested at the IRR itself. A 40% IRR project only lives up to its promise if you can plow the year-one payout back into another 40% opportunity — usually unrealistic. For comparing long-horizon projects, discount the interim flows at your real cost of capital.
Examples
Example 1 — The default five-year annuity. Invest $100,000 at time 0 and receive $25,000 at the end of each of years 1 through 5. The engine solves for r where −100,000 + 25,000·annuity-factor = 0, and reports an IRR of about 7.93%. Total undiscounted profit is $25,000, simple payback is exactly 4.0 years, and against a 10% hurdle rate the result is FAIL.
Example 2 — A high-return small bet. Spend $10,000 today and pull out $5,000 at the end of each of the next five years. The cash-flow stream is −10,000, +5,000 × 5. Solving gives an IRR of about 41.04%. Even though the dollar profit ($15,000) is smaller than example 1, the annualized return is far higher because the money comes back quickly. This is exactly what IRR is good at: ranking projects of different sizes.
Example 3 — A seven-figure project. Commit $1,000,000 upfront and forecast $300,000 of net inflow at the end of each year for five years. The IRR lands around 15.24%, total undiscounted profit is $500,000, and payback is roughly 3.33 years. Against a 10% hurdle the project PASSES comfortably. Larger magnitudes (>= $1,000,000) stress the same arithmetic, which is why the engine uses double-precision bisection rather than hand-rolled rounding.
Example 4 — An uneven ramp. A startup needs $50,000 upfront and pays back $10,000, $15,000, $20,000, $25,000, and $30,000 in years one through five. The engine finds an IRR near 23.29%. Rising cash flows push the breakeven discount rate higher than a flat stream would, because more of the money arrives later — but wait, later cash flows are discounted more heavily, so the IRR ends up between the flat-return and high-return cases.
FAQ
What does IRR actually mean?
IRR is the annualized compound growth rate of a series of cash flows. If you treat the project like a bank account, IRR is the interest rate that would grow your initial deposit to exactly match every future withdrawal and end at zero. A 12% IRR means the project behaves like an investment earning 12% per year, compounded, on the declining balance still inside the deal.
How is IRR different from ROI?
ROI (return on investment) is total profit divided by total cost, expressed as a percentage, with no regard to time. A project that doubles your money in one year and a project that doubles it over ten years both show a 100% ROI, but their IRRs are completely different — roughly 100% versus 7.2%. IRR is annualized and time-weighted; ROI is not.
What is a "good" IRR?
It depends entirely on your hurdle rate and the risk of the project. As a rough rule of thumb: an IRR below your cost of capital destroys value; an IRR a few points above it is acceptable for low-risk projects; an IRR above 20% is strong for private-equity-style deals, but should trigger a close look at whether the projected cash flows are realistic. Compare IRR to your alternatives — a mortgage rate, a bond yield, or a broad index fund's long-run return — rather than to an abstract number.
Can IRR be negative?
Yes. If the total undiscounted cash you walk away with is less than what you put in, the breakeven discount rate goes below zero. A negative IRR means you lost money even before adjusting for inflation or opportunity cost. The bisection solver handles rates down to −99%; below that the cash-flow stream is so bad that the discount factor starts flipping sign and the equation no longer has a meaningful root.
Why is my IRR different from the spreadsheet result?
Three common reasons. First, the cash flows are entered at different points in time — this calculator assumes every inflow arrives at the end of the year, while some spreadsheets let you choose mid-year or beginning-of-year. Second, the initial cost is sign-flipped: make sure the upfront investment is entered as a positive cost here (the engine flips it), not as a negative. Third, extra cash flows that arrive between years 1 and 5 need to be folded into the nearest year's figure.
Should I ever make a decision using IRR alone?
No. IRR is best used alongside the net profit, the payback period, and a qualitative read on how realistic the cash-flow forecasts are. IRR ignores project size (a $10,000 project with a 50% IRR earns less dollar profit than a $1,000,000 project at 15%), ignores reinvestment risk, and can be multiple-valued when cash flows change sign more than once. Use it to rank similar-sized options, then double-check with NPV.
Disclaimer
This IRR calculator is provided for informational purposes only and does not constitute financial, investment, tax, or legal advice. The implied annual return is a mathematical solution based on the cash flows you enter; real projects carry risk, uncertainty, fees, taxes, and reinvestment assumptions that this model does not capture. Always model multiple scenarios and consult a qualified financial professional before committing capital. Past IRRs do not guarantee future results.