Published:
August 18, 2015
Last updated:
November 3, 2026
What Is an Adjustable-Rate Mortgage and How Does It Work?

Key Takeaways

  • An ARM starts with a fixed rate for a set period, then adjusts at scheduled intervals.
  • ARMs often have lower initial rates and payments than fixed-rate mortgages.
  • An ARM may suit borrowers who expect to sell, move, or refinance before the fixed period ends.
  • Borrowers should make sure they can afford possible future payment increases, even with rate caps.
In This Article

An adjustable rate mortgage, or ARM, is a home loan that starts with a fixed interest rate for an initial period and then adjusts on a set schedule. That structure can make an ARM appealing for borrowers who expect to move, sell, or refinance before the fixed period ends, while a fixed-rate mortgage may be safer for those who want predictable payments over the long term. Understanding how an ARM works compared with a fixed rate mortgage can help applicants make a more informed decision about their mortgage plans.

What is an Adjustable-Rate Mortgage (ARM)?

An adjustable-rate mortgage (ARM) is one that comes with an interest rate that will fluctuate periodically over the life of the loan, and the mortgage payment will also fluctuate as a result. With this type of home loan, the interest rate will initially be fixed for a certain period of time. After that period expires, the interest rate will reset over specific intervals.

ARMs are typically expressed with two numbers. The first number represents the initial time period whereby the interest rate remains fixed. It’s this time period that the rate will be what you were initially quoted. Once that period expires, the rate will fluctuate at various intervals. That’s where the second number comes into the picture, which represents how often the interest rate will fluctuate.

For instance, a 5/1 ARM means that the fixed rate will remain in effect for 5 years (represented by the first number) and the rate will change every year (represented by the second number). A 3/1 ARM means that the fixed rate will remain in effect for 3 years and will adjust every year after that 3-year time frame ends.

It should be noted that adjustable-rate mortgage have limits that are set in terms of how high the interest rates or payments can go per year or over the mortgage term.

You can see how this differentiates from a fixed-rate mortgage, which is one with an interest rate fixed for the entire term length. This means that a home loan with a 30-year term has an interest rate that will remain the same for the full 30 years, and this also means that the mortgage payments will remain the same over 30 years.

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How is an ARM Beneficial?

There are several benefits associated with an ARM. For example, the initial interest rate and related mortgage payment are typically lower than with a fixed rate mortgage. In addition, if rates decrease over the life of the loan, the mortgage payment will lower as a result without the need to refinance to take advantage of the lower rate.

An ARM may be ideal for those who are planning to sell their home before the initial time period period is up. In this case, buyers can take advantage of the lower initial interest rate and sell before their interest rate changes (especially if rates are higher and would therefore increase).

Before Applying for an ARM

Before applying for an adjustable rate mortgage, there are a few points that the applicant should keep in mind. Just as the interest rate may go down over the life of the loan, the rate and the mortgage payment may increase. The loan applicant should ensure that the upper limit for the interest rate and mortgage payment will be affordable for their personal budget before applying for this type of loan.

It’s also important to understand that the initial fixed rate that applies to the initial time period can increase in the future when the rate adjusts. This is a risk that borrowers will need to take. But if rates are expected to decrease in the near future, borrowers with an ARM can realize lower rates after the initial time period ends, which can save them money.

Each loan program available to a mortgage applicant has its pros and cons, and this holds true for an adjustable rate mortgage as well. Understanding how each loan program works and what the benefits and drawbacks for each are can help an applicant make an informed decision when applying for a mortgage. Those who are interested in applying for a new mortgage for a purchase or a refinance in the coming days or weeks may reach out to Seattle mortgage broker to inquire about the different loan programs available in Seattle.

Should You Choose an ARM or a Fixed-Rate Mortgage?

An ARM may be a better fit if you expect to stay in the home for a shorter time, think you may sell or refinance before the initial fixed period ends, and are comfortable with the possibility that your payment could change later. A fixed-rate mortgage may be the better choice if you expect to keep the loan for many years, want steady monthly payments, or prefer more certainty in your long-term housing budget. In general, the shorter your expected time in the home and the more flexibility you have in your budget, the more an ARM may be worth considering. The more important payment predictability is to you, the more a fixed-rate loan may make sense.

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Have Questions About Mortgages?

Sammamish Mortgage can help. We serve clients across Washington, Idaho, Colorado, Oregon, and California. Since 1992, we’ve been providing several mortgage programs and products with flexible qualification criteria to borrowers across the Pacific Northwest. Visit our website to get an instant rate quote or to use our online mortgage calculator. Or, reach out to us if you are ready to get pre-approved for a mortgage.

FAQs

What is an adjustable-rate mortgage?

An adjustable-rate mortgage, or ARM, is a home loan that begins with a fixed interest rate for an initial period and then adjusts on a set schedule after that period ends. When the interest rate changes, the mortgage payment can change as well.

What is the difference between a fixed-rate mortgage and an adjustable-rate mortgage?

A fixed-rate mortgage keeps the same interest rate for the full loan term, so the principal and interest payment stays predictable. An adjustable-rate mortgage starts with a fixed rate for a limited time and then resets at scheduled intervals, which means the rate and payment may go up or down later.

What do the numbers in a 5/1 ARM mean?

In a 5/1 ARM, the first number means the interest rate stays fixed for 5 years. The second number means the rate adjusts every 1 year after the fixed period ends.

How long does an adjustable-rate mortgage last?

An ARM lasts for the full loan term unless it is paid off, sold, or refinanced earlier. What changes is not the loan length itself, but the point at which the interest rate stops being fixed and begins adjusting on a set schedule.

How often can an ARM payment change after the fixed period ends?

That depends on the loan structure. For example, with a 5/1 ARM, the payment may change once a year after the first 5 years because the interest rate adjusts annually.

What are ARM rate caps?

ARM rate caps are limits on how much the interest rate or payment can increase each year or over the life of the mortgage. They help limit how high adjustments can go, but borrowers still need to make sure the possible maximum payment would fit their budget.

When does an adjustable-rate mortgage make sense?

An ARM may make sense for a borrower who expects to move, sell, or refinance before the initial fixed period ends. It can also appeal to someone who wants a lower starting rate and understands that the payment may change later.

Is an adjustable-rate mortgage ever a good idea?

Yes, it can be a good idea in the right situation. An ARM may work well for borrowers who do not expect to keep the loan long term, who want a lower initial payment, or who believe they may refinance or sell before the rate begins adjusting.

Can you refinance out of an ARM before the rate adjusts?

Yes, borrowers may be able to refinance before the initial fixed period ends. That is one reason ARMs are sometimes used by people who plan to change loans later, although refinancing depends on market conditions, qualification, and timing.

Can I pay off a 5-year adjustable-rate mortgage early?

A borrower can pay off an ARM early by selling the home, refinancing, or otherwise satisfying the loan balance, subject to the loan terms. Many people choose an ARM because they expect to exit the loan before the fixed period ends, but the specific mortgage documents should always be reviewed for any loan-specific conditions.