IRR (Internal Rate of Return) is the discount rate that makes the NPV of a series of cash flows equal to zero. In other words, it is the annualized compounded return rate the investment is expected to generate over its life.

How does the Newton-Raphson method find the IRR?

The algorithm starts with an initial guess (10%), then iteratively refines it by computing NPV and its derivative with respect to the rate. Each step adjusts the guess by NPV / NPV' until the result converges to within a very small tolerance (typically 1e-7). It usually converges in fewer than 100 iterations.

What does it mean when no IRR is found?

Some cash flow patterns — such as all-positive or all-negative flows, or flows that change sign more than once — may produce multiple IRRs or no real IRR. In these cases the calculator displays a warning and you should use NPV analysis with an explicit discount rate instead.

How is IRR different from ROI?

ROI is a simple ratio of profit to cost and ignores the time value of money. IRR accounts for the timing of cash flows, making it a more rigorous measure for multi-period investments. A high ROI project might have a lower IRR if the gains are far in the future.

Should I accept a project if IRR > cost of capital?

Generally yes — if IRR exceeds your hurdle rate (cost of capital or required rate of return), the project adds value. However, always cross-check with NPV analysis, especially when comparing mutually exclusive projects of different sizes or durations.

Can I use IRR for irregular time periods?

This calculator assumes equally spaced periods (annual, quarterly, etc.). For irregular dates, you need the XIRR function. The period label here is abstract — if your flows are quarterly, the resulting IRR is a quarterly rate; multiply by 4 (or compound) to get an annual figure.

IRR Calculator (Internal Rate of Return)

Name: IRR Calculator (Internal Rate of Return)
Availability: InStock
Author: Nham Vu

Enter an initial investment and future cash flows to instantly calculate the Internal Rate of Return (IRR) — the discount rate at which NPV equals zero.

Cash Flow Inputs

Hurdle Rate / Cost of Capital (%) (optional)

Used only to compare against the computed IRR.

Cash Flows by Period Period 0 = initial investment

Enter cash flows on the left and click Calculate IRR.

Period 0 should be your initial investment (negative).

Internal Rate of Return

0.00%

IRR

—

Hurdle Rate

—

Spread

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Cash Flow & Discounted Value at IRR

Period	Cash Flow	Discount Factor	PV at IRR

NPV Sensitivity to Discount Rate

The IRR is where the curve crosses zero.

Summary