The Extended Internal Rate of Return (XIRR) is a sophisticated financial metric used to calculate the annualized return of an investment portfolio where cash flows are irregular and do not occur at fixed intervals. This makes it far more practical for real-world investment scenarios than the standard IRR function, which assumes periodic cash flows. XIRR is the perfect tool for accurately measuring the performance of your personal investment portfolio, where you might invest or withdraw money on random dates. To use the XIRR Calculator, you need to provide a series of cash flows and the exact date for each one. The interface allows you to add multiple cash flow entries. For each entry, you must input the 'Amount' and select the corresponding 'Date'. A crucial rule is that cash outflows (investments you make) should be entered as negative numbers, while cash inflows (withdrawals or dividends you receive) should be entered as positive numbers. Your very first entry should typically be your initial investment, entered as a negative value. You must have at least one positive and one negative cash flow for the calculation to be possible. You can add as many cash flow rows as needed using the 'Add Cash Flow' button. After you have listed all your transactions, click 'Calculate XIRR'. The tool will then use an iterative method (like the Newton-Raphson method) to find the single annualized rate of return that makes the net present value of all these cash flows equal to zero. The result is displayed as a percentage, giving you a true, time-weighted performance measure of your investment portfolio.