Fixed-Rate Mortgages Explained
A fixed-rate mortgage locks in your interest rate for the entire life of the loan, meaning your monthly principal and interest payment never changes. The most common terms are 15-year and 30-year fixed-rate mortgages. A 30-year fixed offers lower monthly payments but more total interest paid, while a 15-year fixed has higher payments but significantly less total interest.
Fixed-rate mortgages provide predictability and peace of mind. You know exactly what your housing cost will be for years or decades into the future, making budgeting straightforward. This stability comes at a cost, as fixed rates are typically higher than the initial rates on adjustable-rate mortgages.
Adjustable-Rate Mortgages (ARMs) Explained
An adjustable-rate mortgage (ARM) features an interest rate that changes periodically based on a benchmark index plus a margin set by the lender. ARMs start with a fixed-rate introductory period, typically 3, 5, 7, or 10 years, during which the rate is usually lower than comparable fixed-rate mortgages.
After the introductory period, the rate adjusts at specified intervals, usually annually. ARMs have caps that limit how much the rate can change per adjustment period and over the life of the loan. For example, a 5/1 ARM has a fixed rate for 5 years, then adjusts annually. A 5/6 ARM adjusts every 6 months after the initial period.
Comparing Costs: Real Numbers
Consider a $400,000 mortgage. At a 7% fixed rate over 30 years, your monthly payment is approximately $2,661, and you would pay about $558,036 in total interest. With a 5/1 ARM starting at 6.25%, your initial monthly payment is approximately $2,462, saving you $199 per month for the first five years, totaling nearly $12,000 in savings.
However, if the ARM rate adjusts to 8% after year five, your payment jumps to approximately $2,791, costing you $130 more per month than the original fixed rate. The actual outcome depends entirely on where interest rates go after your introductory period ends, which nobody can predict with certainty.
When Fixed-Rate Makes Sense
Choose a fixed-rate mortgage if you plan to stay in your home for a long time, as the rate stability becomes more valuable over longer periods. Fixed rates are also preferable when current interest rates are historically low, since you lock in that favorable rate permanently. If you have a tight budget with little room for payment increases, the predictability of a fixed rate provides essential financial security.
Fixed-rate mortgages are also the safer choice during periods of rising interest rates or economic uncertainty. If you value simplicity and do not want to monitor interest rate trends or worry about future payment changes, a fixed rate eliminates that concern entirely.
When an ARM Makes Sense
An ARM can be advantageous if you plan to sell your home or refinance before the introductory period ends. If you are confident you will move within 5 to 7 years, the lower initial rate saves money without exposing you to rate adjustment risk. ARMs also make sense when interest rates are high and expected to decline, as your rate would adjust downward.
Borrowers who expect significant income growth may also benefit from ARMs, as they can handle potential payment increases. Additionally, if you plan to make large extra principal payments early on, the lower initial rate lets more of your payment go toward principal, building equity faster.
Key Questions to Ask Your Lender
Before choosing a mortgage type, ask your lender several critical questions. What is the rate difference between fixed and ARM options? What index does the ARM use, and what is the margin? What are the adjustment caps, both per period and lifetime? What is the worst-case scenario for the ARM payment after all adjustments?
Also ask about prepayment penalties, which can affect your ability to refinance or make extra payments. Understand the total cost of each option over the time you plan to own the home, not just the monthly payment. Finally, ask about rate lock options and how long you have to close at the quoted rate.