An adjustable-rate mortgage — also called an ARM — is a home loan where your interest rate can change over time. It starts with a fixed rate for a set period, then adjusts up or down based on market conditions. In 2026, ARMs are worth understanding if you want a lower starting rate or plan to sell or refinance before the adjustment period kicks in.
How an ARM Works
An ARM has two phases:
- Fixed period: Your interest rate stays the same. This can last 3, 5, 7, or 10 years depending on the loan you choose.
- Adjustment period: After the fixed period ends, your rate adjusts periodically — usually every 6 months or every year — based on a market index plus a margin set by your lender.
ARMs are often described with two numbers, like 5/1 or 7/6. The first number is how many years the rate is fixed. The second is how often it adjusts after that.
Examples:
- A 5/1 ARM: Fixed rate for 5 years, then adjusts once per year.
- A 7/6 ARM: Fixed rate for 7 years, then adjusts every 6 months.
ARM Caps: How Much Can Your Rate Change?
ARMs have built-in limits called caps that protect you from extreme rate increases. There are three types:
- Initial cap: The maximum the rate can go up at the first adjustment. Often 2% to 5%.
- Periodic cap: The maximum the rate can increase at each subsequent adjustment. Often 1% to 2%.
- Lifetime cap: The maximum the rate can rise over the life of the loan. Often 5% to 6% above the starting rate.
For example: If you start at 5.5% with a 2/1/5 cap structure, your rate can rise at most 7.5% at the first adjustment, no more than 1% per adjustment after that, and no more than 10.5% over the life of the loan.
ARM vs. Fixed-Rate Mortgage
Here is a simple comparison:
- Fixed-rate mortgage: Same interest rate for the entire loan term (15 or 30 years). Predictable payments. Better if you plan to stay in the home long-term or if rates are low and expected to rise.
- Adjustable-rate mortgage: Lower starting rate than a fixed-rate loan. Payments may increase after the fixed period. Better if you plan to sell or refinance before the adjustment period, or if rates are high and expected to fall.
In 2026, if the 30-year fixed rate is significantly higher than the 5/1 ARM rate, the ARM can save you thousands of dollars during the initial period.
When an ARM Makes Sense
An ARM can be the smarter choice in these situations:
- You plan to sell the home within 5 to 7 years (before the rate adjusts).
- You expect to refinance before the fixed period ends.
- You expect interest rates to fall — which would lower your payments at adjustment time.
- You want the lowest possible payment now and are comfortable with uncertainty later.
When to Avoid an ARM
- You plan to stay in the home for more than 10 years.
- Your budget is tight — a rate increase could make your payments unaffordable.
- You want payment certainty above all else.
- You are buying at the top of your budget and have no room for a rate shock.
Current ARM Rates in 2026
As of early 2026, the average 5/1 ARM rate is running roughly 0.5% to 1% lower than the 30-year fixed rate. On a $400,000 loan, that difference can mean $150 to $300 less per month during the fixed period. Whether that savings outweighs the risk of future rate adjustments depends on your timeline and risk tolerance.
Bottom Line
An ARM is not inherently risky — it just requires that you understand the terms. If you buy a home knowing you will sell in 5 years, a 5/1 ARM can save you real money compared to a 30-year fixed rate. If you plan to stay for decades, a fixed-rate mortgage offers peace of mind. Talk to at least three lenders and compare both options before you decide.