We're always looking for tools and information to help investors calculate their "Retirement Number."  Most brokerage and mutual funds companies are providing tools on their websites for this calculation.  Our Calculators, Links and Tools page will provide a good overview too.

Here's a quick way to calculate your number in today's Sunday newspaper. 

Courtesy of the Wall Street Journal

Let's see what this math would look like for a couple -- we'll call them Andrea and Scott -- who are a year or two away from retirement and are making about $80,000 (combined) a year: Multiplying that income by 0.8 shows they will need $64,000 a year in retirement. Multiplying $80,000 by 12 shows they will need a nest egg of $960,000.

It's important to note that we start with a big assumption: that the average American can, in fact, live comfortably on 80% of his or her pre-retirement income in retirement itself. While the rule of thumb has long been that most of us will need about 70% to 80% of our pre-retirement earnings once we leave work, this assumes that about 20% to 30% of our money while we're working goes to things like taxes, transportation and savings and that all those bills will drop off in retirement.