Finance Calculators
IRR Calculator
The internal rate of return is the discount rate that makes the net present value of a series of equal-interval cash flows zero. This calculator also reports the modified internal rate of return at the finance and reinvestment rates you choose, and the net present value at any discount rate, while stating the limits of its numerical search.
Calculator
Formulas, assumptions and search limits
IRR solves NPV(r) = Σ CFᵢ / (1 + r)^i = 0 for r, where CFᵢ is the cash flow of period i and period 0 is the first entry: −10,000 then 3,000, 4,000, 5,000 and 6,000 give NPV(24.8883%) ≈ 0, so the IRR is 24.8883%. MIRR separates how a project is financed from how its returns are reinvested: MIRR = (FV ÷ −PV) ^ (1 ÷ (n − 1)) − 1, where PV discounts the negative flows to period 0 at the finance rate, FV compounds the positive flows to the last period at the reinvestment rate and n is the number of flows — at 10% and 10% on the same flows it is 19.4127%. Net present value at the discount rate is Σ CFᵢ / (1 + r)^i — 3,887.71 at 10%. The solver scans 8,192 equally spaced points in ln(1+r) over rates from −99.999999% through 1,000,000%, then bisects sign-change intervals for up to 100 iterations per bracket (or until the ln(1+r) interval is narrower than 10⁻³). It does not prove that roots were not missed between samples, tangent roots, or roots outside the range; one found root is not proof of global uniqueness. Rates must exceed −100%. Taxes, fees and inflation are not inferred.
About This Calculator
What It Does
The internal rate of return (IRR) is the constant discount rate that makes the net present value of a series of equal-interval cash flows zero. This calculator also computes the modified internal rate of return (MIRR) with separate finance and reinvestment rates, and the net present value (NPV) at any discount rate you choose. Each amount uses the same currency, shown from this page’s country context; the country does not change the mathematics.
Worked Example
Enter −10,000 in period 0 and 3,000, 4,000, 5,000 and 6,000 in periods 1 to 4. At 24.8883% the net present value is zero, so the IRR is 24.8883%. At the finance and reinvestment rates of 10% the modified rate is 19.4127%, and at the discount rate of 10% the net present value is 3,887.71.
Real-World Usage
Compare projects that cost money up front and pay back in equal instalments, or set a hurdle rate and check whether a project’s IRR clears it. When a pattern changes sign more than once, review every reported rate before interpreting it.
Local Context
The currency symbol and number formatting follow the selected country and language. The rates are yours to set; all flows must be in the same currency for the result to mean anything. Taxes, fees and inflation are not inferred. The finite scan covers −99.999999% to 1,000,000% at 8,192 log-rate samples and can miss tangent, between-sample or out-of-range roots.
Last reviewed: November 2026.
For information only, not investment, tax or financial advice.
Frequently Asked Questions
What does this IRR calculator calculate?
It finds the rate that makes the net present value of equal-interval cash flows zero, and also reports the modified internal rate of return at the rates you set and the net present value at any discount rate.
Why can an IRR have more than one answer?
When the cash flows change sign more than once, the NPV equation can cross zero at several rates. This calculator lists the rates it finds instead of selecting one, and its finite scan may miss roots.
Does this include taxes, fees or inflation?
No. Enter those cash flows yourself if appropriate; the calculator does not infer taxes, fees, inflation, currency conversion or investment risk.
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