Assuming an annual return of 12%, you would be able to create a corpus of Rs 75.69 lakh by investing RS 15,000 every month for the next 15 years. However, this is will not be enough to take care of your retired life. You should find out your current cost of living – calculate how much money you need to live comfortably today. Find out the annual cost and provide for an annual inflation of 6-7% for 15 years. This will help you to find out the annual living expense needed after 15 years. For example, if your annual living expense is Rs 5 lakh, you will need Rs 10.39 lakh after 15 years. This is the impact of an annual inflation of 6% on your living expenses. If you assume that you are going to live for another 20 years, you need around Rs 2.08 crore (Rs 10.39x20). To create that corpus, you need to invest around Rs 1 lakh every month for the next 15 years. We are assuming an annual return of 12% on your investments.
Note, this is a rough calculation. You need to seek the help of an investment advisor or use a good online retirement calculator to find a personalised solution.