Here's a question heard over and over again: How do I get a more affordable monthly mortgage payment? So let's look at the three factors affecting your monthly payment, then conclude with a look at your down payment.

Before we begin, it might be a good idea to visit my Web site at www.money99.com and find our FREE CALCULATORS under the additional resources button. There you can enter an unlimited number of variables

to see how your monthly payment is affected.

The three factors which have a direct impact on your payment are the number of payments, the interest rate, and the loan amount.

As you decide how many payments you will be making, keep in mind that lenders offer three primary loan terms: 30 years, 20 years and 15 years. One lender told me they offer a 10-year loan but that the rate is typically identical to that of the 15-year loan.

In the Atlanta market, the most popular term by far is 30 years. In fact, the only benefit to accepting a 15- year term is a slightly reduced interest rate, typically about half a percent less than the 30-year program. In exchange for that interest rate savings, your monthly payment of principal and interest may be as much as 40 percent higher each month.

For example, if you borrow $100,000 at 6 percent for 30 years, your monthly loan payment would be about $600. But if you substituted a 15-year payback and received the same loan at 5.5 percent, your payment would jump to about $817, an increase of about 36 percent. At an equivalent 6 percent rate, that differential exceeds 40 percent.

I kneow the entire difference is faster payback of principal, and that fact can help you avoid thousands in excess interest fees, but a 36 percent jump puts homeownership out of the reach of many.

The next factor that affects payments is the interest rate, and that amount is largely beyond our control.

I use the term "largely" because there are some options we have when deciding on interest rate, but picking a lower rate may have serious consequences.

For example, the prevailing 30-year fixed rate in metro Atlanta today is being offered at a rate of about 6 percent. We can lower that rate by about half a percent if we accept a shorter payback term of 15 years, but that causes our payments to jump. But there is another way to lower the rate even more and still keep a 30- year term.

That loan is called the "five-year balloon" program, and it is calculated as if it were going to last 30 years. The interest rate offered with this loan is typically almost a full percentage point below that of the 30-year fixed rate, making it an attractive 5 percent. But there is a catch.

With the five-year balloon program, the loan is designed to mature in exactly five years. So you would need to sell, refinance with another loan or find another way to pay off the loan after 60 months. And trust me, 60 months passes very quickly when you know you have a big bill to pay at the end of the term.

The five-year balloon loan is appropriate only when you are sure you will be selling within five years. For example, if your boss tells you it is highly likely you will be transferred in five years, then a loan like this might be good. Even so, people's lives change, and you may end up changing jobs before five years, or your boss may change his mind.

With interest rates at about their lowest in many years, my advice is to focus on the popular 30-year fixed rate, then sleep well knowing that your monthly payment amount can never go up unless you choose to pay it off more quickly.

Finally, your loan payment is directly affected by the amount you are borrowing, called your "loan amount." It is typically the amount left after you subtract your down payment from the proposed purchase price.

What if you have more available than the standard 5 percent, 10 percent or 20 percent down payment? Does it make sense to put down as much as possible?

That depends on your financial goals and your ability to make wise money choices. The best bargain available in long-term financing is the 80 percent loan spread over 30 years. This avoids additional costs for mortgage insurance but spreads fixed closing costs over the maximum amount of dollars.

Talk with your financial advisers to find out what options are available, and select the best combination of term, rate and amount you can find.

 John Adams is a broker and investor.