Gather as much basic information as possible
To use a retirement calculator, you'll need to plug in some basic information about your finances as well as your spouse's if you're married. These usually include salaries, percentage of income saved per year for retirement, how much you have in your retirement accounts (such as 401(k)s and IRAs), whether you expect to receive a pension and how much it will be and your expected Social Security benefits. If you've worked full-time for at least 10 years, you can use the Social Security Administration's online tool to get an estimate of your benefits.
Adjust your numbers to see what can effect any changes
If you make adjustments to the numbers you input, it's easy to see what effect they'll have on your retirement planning, The Motley Fool says. So if a calculator predicts a shortfall between what you're likely to save and what you're likely to need, switch up some numbers. See what working longer, changing your spending or investing more has on the outcome.
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Think about how your spending will change in retirement
It's hard to calculate what your expenses will be in retirement, but it's an important part of the equation. USA Today suggests asking yourself questions such as whether you'll have paid off your mortgage, will spend more on health care or will spend less on insurance and possibly taxes. Once you figure out how much money you're likely to spend each month, you can turn that into an annual estimate.
Try different calculators
Retirement calculators can differ when it comes to the information they ask for and the numbers they assume, such as the interest rate you're likely to earn on investments and the number of years you'll probably live. It's best to try several different calculators, because the results they generate certainly aren't exact, The Motley Fool says.
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Revisit the calculators at least once a year.
Retirement calculators make certain assumptions about your finances and lifestyle that may change over time. That's why linkfinancialadvisory.com advises using calculators annually and changing information as needed. For example, AARP's retirement calculator assumes a 6% rate of return earned on your investments before retirement, an annual raise rate of 2.5% a year and an inflation rate of 2.5% a year. It also sets a default retirement age of 67 unless you change it. These numbers are estimates, and they may need adjustments over time.