Your retirement calculator is probably giving you wrong answers and you don't know it. Almost every free Internet retirement calculator I evaluated is inaccurate. This is shocking when so many people are using these calculators to plan their retirement years. By the time they discover the errors it may be too late.

Why does just about every retirement calculator give incorrect or incomplete answers? Because they are not really designed to perform accurate long-term calculations. Rather, most are designed as a sales tool to attract you to do business with the company that sponsors the calculator on its website. For those of you who are fishermen or fisherwomen, the calculator is the "bait". You enter the limited amount of requested data into the calculator, and it tells you that your retirement is headed for disaster. You panic at this revelation. The company then "sets the hook" by offering to help you formulate a plan for your retirement so you will be able to live very well in your retirement years.

Another inaccuracy of most retirement calculators is the amount of replacement income the calculator recommends. Replacement income is the amount of income you will require in retirement to maintain your preretirement standard of living. Replacement income is usually stated as a percentage of your working income before retirement. A very common percentage for replacement income is seventy-five percent (75%). Solid research shows that you can retire on much less than the 75 - 80% replacement income recommendation used by the financial services industry.

A couple of "do not's" for you to consider:

Do not trust your future retirement to a retirement calculator that asks for five to eight inputs and then calculates the answer. That is not enough data to accurately calculate your retirement and you put your entire retirement at risk.

Do not trust a retirement calculator that is sponsored by a company that can sell you financial services.

If you want a quick snapshot of your retirement plan, use the American Association of Retired People Retirement Calculator or the CNN Money Retirement Calculator. However, do not use these for serious, long-term retirement planning.

Look for a retirement calculator that has most of the following features:

• It should allow you to enter your information and your spouse's information separately.

• It should allow for income from a retirement job and have a start date and a stop date for that income.

• It should have an allowance for lump-sum changes to your portfolio. This could be the proceeds from the sale of your home. An event of this size makes a significant difference in your retirement plan.

• It should allow for Social Security input for both you and your spouse.

• It should include inputs for pensions (if applicable).

• It should allow you to select different spending models for your retirement (Examples: Constant, Bernicke's, Percentage of Remaining Portfolio)

• It should allow you to specify the type of portfolio you hold (Conservative, Moderate, Aggressive)

Make no mistake. Using the best retirement calculator will require work on your part. You will need to do your homework and properly prepare the input for the calculator. However, you are planning the last years of your and your spouse's lives and you want those years to be the very best for both of you. You two deserve nothing less.