According to Home & Family Finance, the general rule says you will need 70% to 80% of your pre-retirement income each year to maintain your current standard of living. If you can expect a 4% increase in salary each year, your income will double every 18 years. So if you're 47 and earning $40,000 today, your income at age 65 is likely to be $80,000. That would translate to a need for $56,000 to $64,000 per year.

However, that's just a rough estimate. You will be well advised to develop your own estimate based on your particular situation and needs. For instance, if your main retirement recreation will be fishing your local lake, that will be obviously less expensive than going on foreign cruises.

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