YOU PROBABLY have seen the TV ads and read the articles saying that saving for retirement is important. You know you need to start planning for the day you leave the workforce, but just how to begin?

Marc A. Hebert's Money Sense column sig

First, understand that retirement planning is not an exact science. You will be planning for potentially many years in the future and many unknowns. The key is to do the best you can.

To begin, it is a good idea to have an estimate of your expenses during retirement. Your current spending makes for a good starting point. While retirement changes some aspects of your lifestyle, many items will remain the same.

Some expenses will likely be less though. For example, you will no longer need those work clothes. You might spend less on gasoline for the car, as there are no more daily commutes.

On the other side of the coin, maybe you would like to travel more extensively. Maybe there will be more trips to see the children and grandchildren that involve travel to other states.These are some factors that will increase your expenses.

Some of the common expense areas are food, clothing, housing, utilities, transportation, taxes, debt, insurance and recreation.

You will want to review the cost of health care carefully. These costs can increase substantially as you age, and you will need a plan to deal with it.

Within each category, estimate how much you are spending now and determine as best you can how much you might spend during retirement. This will give you a base number to start your retirement planning. Don’t forget to think about inflation. Inflation has averaged 2.1% per year over the last 20 years.

Your expenses might also change over time. Maybe your mortgage will be paid off. Items like these can be factored into your retirement expenses.

Several variables will affect your retirement outflows. One is when you plan to retire. Retiring at age 50 requires more money that at age 65. There are more retirement years to support as you will be retired a lot longer.

The other item that will affect the length of your retirement is your life expectancy. We never know the exact date we will die, but everyone can hope for a good long life. It is best to plan for a longer life than to run out of money because you didn’t do so.

To estimate your life expectancy, you can find government statistics or life insurance tables that can give you a clue. Maybe your family history can help tell you if longevity is in your genes.

Once you have a good handle on your expenses and how they might increase over time, you need to evaluate how you might pay for them. The first resource is Social Security. You can visit the Social Security Administration website (www.ssa.gov) to get an estimate of what you will receive at various retirement dates.

Another source, although becoming less common, is a traditional pension benefit. You might have an IRA or 401(k) at work that will provide you retirement income. Estimating the income you receive from an IRA or 401(k) is difficult because it depends on the amount invested, rate of return and other factors. Just do the best you can with the estimate.

If your income doesn’t cover your expenses, then now is the time to try and make up the difference. You might review your expenses to see where you could cut down. You might delay your retirement, for example. You might be able to save more. You could also choose to do a phased-in retirement, working part time for a few years.

Marc A. Hebert, MS, CFP, is a senior member and president of the wealth management and financial planning firm The Harbor Group of Bedford. Email questions to Marc at mhebert@harborgroup.com. Your question and his response might appear in a future column.