Even though the calculations cannot be precise we can work with certain pointers. By the time we retire, we would have fulfilled almost all our responsibilities. Children will have completed their education or will be about to complete. Most chances are that they will be settled. By the time of retirement, loans will have been paid off.

See what you need now to maintain your lifestyle after deducting the liabilities. This can be called the cost of living today. Keep in mind that medical costs will increase as we age. Once you calculate your present cost of living, add to it the inflation.  As certain experts suggest, assuming rate of inflation to about 4% is safe enough. Also include the duration or the number of years for which you expect to need this income and that is the most difficult part.

At this stage it is important to factor in the returns and income you may be receiving from other sources like property, investments, stocks, or FDs. You will also get some retirement benefits from your employer in the form of PPF accumulated during your employment and gratuity.  These help calculate how much pension income you can actually expect coming in for a given number of years.

Check out if there is a deficit in what is needed and what you may be getting and start filling the gaps now.