It's easier to calculate returns from a mutual fund scheme when there is one investment date and one redemption date. But calculating systematic investment plan (SIP) is tricky because you invest every month. But Microsoft Excel makes it easy. Using the Extended Internal Rate of Return (XIRR) function, you can calculate returns from any investment where there are multiple inflows or outflows. Just enter all your investment (make sure you put them down as negative values, as they indicate outflows), and one final redemption figure (as a positive value). A guess value, part of XIRR formula, needs to be keyed in.