XIRR refers to the extended internal rate of return. XIRR usually calculates returns on investment where there are multiple transactions taking place in different times. In simple terms, XIRR can be used to calculate consolidated returns when you buy units in mutual funds or may sell. You can calculate the XIRR in mutual funds or investment through formula in excel, which is “=XIRR (values, dates, guess). The XIRR method of calculating returns simplifies the process in case of irregular investment. The XIRR formula will modify the internal rate of interest (IRR) and enable you to allocate separate dates to individual cash flows.