Social Security will provide you with roughly one-third to one-half of your retirement income. Your savings and pension will provide the rest.

You can get your estimated benefit from the Social Security Administration Website. There are three online calculators you can use.

The Quick Calculator, will ask only for your date of birth and current annual income. Of course it must make certain assumptions about your earnings history, and therefore is less accurate, but it is very easy to use.

The Online Calculator will ask you to enter your annual income for your entire working history since 1950. For each and every year you've worked, enter your total earned income. Of course this takes a lot more work, and you may no longer have your records, but if you can do it it's worth taking the time.

The Detailed Calculator requires a download to your desktop. This is the most accurate (and complex) calculator of the three, but comes closest to the system the SSA uses to determine your actual benefit.

Click here to open the Social Security Website in a new window. From there, choose either the Quick Calculator or the Online Calculator. For the Quick Calculator, enter your date of birth and current annual income. For the Online Calculator, enter your date of birth, age at which you expect to retire, and your complete annual earnings history. In both cases, ask to see results in current dollars, not future inflated dollars. The calculator will then display your estimated monthly benefit. Multiply this figure by twelve for your annual benefit, then subtract that amount from your required annual income.

For example, Emily will use the Quick Calculator and enter her birthdate as January 1, 1970, and her current income of $32,000. According to the calculator, her benefit is estimated at $1,202 a month, assuming she retires at the standard retirement age (67 for anyone born in 1960 or later). That means her annual benefit will be $14,424.

We've already decided she'll need to replace 90% of her $32,000 salary, or $28,800. Social Security will replace $14,424, so her 401(k) nest egg will have to provide her with another $14,376.

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