The amount required to invest monthly in SIP to reach ₹50 lakh in 15 years is directly linked to expected return rate. If the funds earn around 9% a year, one needs to invest nearly ₹13,213 every month. At an 11% return, the required monthly SIP is about ₹10,996. At 12% return, a monthly SIP of about ₹10,008 is needed.