What is a 5/1 ARM? Complete guide to adjustable-rate mortgages

Compared to a standard 30-year mortgage, a 5/1 ARM can offer lower monthly mortgage payments. A 5/1 ARM may also help you afford higher home prices.

These benefits come with a tradeoff: Unlike a 30-year fixed rate, a 5/1 ARM’s rate could go up in five years, increasing your house payment.

Should you trade 30 years of interest rate certainty for five years of saving money? For some home buyers, the answer is yes. This complete guide to adjustable-rate mortgages can help you decide.

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5/1 ARMs: How the numbers work

A 5/1 adjustable-rate mortgage, or 5/1 ARM, begins with a fixed mortgage rate. This fixed rate stays in place for five years.

Since the interest rate stays the same, the monthly payment due to principal and interest will stay the same during the loan’s first five years.

Then, at the end of the loan’s fifth year, the 5/1 ARM’s initial rate expires. The loan then takes a new interest rate for the next year. After that, the rate adjusts once a year for the life of the loan, meaning the loan’s payment amount could change every year.

Will a 5/1 ARM’s rate go up or down?

Any time the ARM’s rate changes, the rate could go up or down. ARM rates are based on three factors:

• The index rate: The index rate is the foundation of the 5/1 ARM rate. Most new ARMs index to the Federal Reserve’s Secured Overnight Financing Rate, or SOFR. This is the rate we hear about on the news every couple months when the Fed meets.
• The margin: The margin is what the lender adds to the index rate. If the index rate adjusts to 5 percent, and the lender’s margin is set at 2.5 percent, the new ARM rate will be 7.5 percent. The margin stays the same for the life of the loan, and its size depends on the borrower’s credit score, down payment size, monthly debts at closing, and lender-specific rules.
• Rate caps: Rate caps, created after the 2008 housing market collapse, limit how high an ARM’s rate can climb. If your ARM’s initial rate is 5 percent and your loan caps the first rate change at 2 percent, the rate will not adjust beyond 7 percent, even if the index and margin say the loan should adjust higher.

Whether an ARM’s rate adjusts up or down depends a lot on market timing. For instance, a borrower who closed an ARM in 2022, when rates were at historic lows, will likely experience a rate increase when the loan adjusts.

Likewise, someone who closed an ARM in 2025, when rates were higher, could see a rate decrease when their loan adjusts.

More about an ARM’s rate caps

Rate caps protect ARM borrowers from feeling the effects of runaway mortgage rates. An adjustable-rate mortgage comes with three separate rate caps. For a loan with a 2/1/5 cap, for example:

• The first cap limits the ARM’s initial rate adjustment. With a 5/1 ARM, this adjustment happens after the loan’s fifth year. To stay under a 2/1/5 cap, this first adjustment can’t add more than 2 percent to the intro rate.
• The second cap limits each annual rate change after the first rate change. With a 5/1 ARM, the middle number in a 2/1/5 cap prevents annual changes from increasing more than 1 percent per year.
  – The last cap is the lifetime cap. It limits how high the rate can climb throughout the life of the loan, even if the loan lasts 30 years. A 2/1/5 cap means the loan’s rate can never climb more than 5 percentage points higher than its intro rate.

These caps help prevent knee jerk rate changes like the ones some borrowers experienced before the 2008 housing market collapse.

5/1 ARM vs. 30-year fixed — when does each loan make sense?

Most home buyers, especially first-time buyers, use 30-year fixed-rate mortgages. A 30-year fixed locks a mortgage rate that lasts for the entire life of the loan, providing rate stability that a 5/1 ARM can’t offer.

That said, a typical 30-year fixed rate will lock higher than the introductory rate on a 5/1 ARM. In exchange for this higher rate, 30-year fixed borrowers get simplicity and rate stability that can last three decades.

Who should use a 30-year fixed?

Borrowers who want to close their loan, make its monthly payments, and never think about mortgage rates again should get a 30-year fixed rate loan. Unless they choose to refinance, the rate they pay will stay the same.

Who should use a 5/1 ARM?

A home buyer who has a specific goal that a 5/1 ARM’s lower intro rate can help achieve should consider this alternative loan. These goals can include:

• Qualifying for a bigger loan: An ARM’s lower initial interest rate can unlock more borrowing power, allowing people to buy more expensive homes. Homebuyers who use this strategy often expect to be earning more money in five years, when the loan adjusts.
• Saving money every month: Lower interest rates on a 5/1 ARM allow lower monthly payments when comparing loans for the same home. Yes, the intro rate will expire in five years, but by then the homeowner could refinance into a fixed rate.
• Owning the home temporarily: A buyer who plans to sell the home within five years can save money with a 5/1 ARM. If they plan to sell the home in a few years anyway, why pay extra for 30 years of stability?
• Savings before a refinance: A buyer who knows they want to refinance within five years could save money with the ARM’s lower initial rate.
• Accelerating equity: A lower minimum payment, allowed by a lower 5/1 ARM rate, could free up cash each month to pay directly on the loan’s principal, speeding up equity growth before a refinance or sale.

These strategies have one thing in common: They use the 5/1 ARM temporarily. In other words, these buyers plan to benefit from the ARM’s lower upfront costs without keeping the loan long enough to experience the tradeoff: the potential for rate volatility.

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What other ARM terms exist?

Most lenders offer a variety of adjustable-rate mortgages. Typical ARMs include the 10/1, 7/1, 5/1, and 3/1. The key difference is the length of the initial fixed rate period. 7/1 ARMs or 10/1 ARMs extend the 5/1 ARMs fixed rate period. A 3/1 ARM locks in a rate for only three years.

Usually, longer fixed rates periods mean higher initial rates, but even a 10/1 ARM could lock in a lower rate than a 30-year fixed.

A less common type of ARM is the 7/6. This loan keeps its initial rate for seven years and then adjusts every six months instead of once a year.

Borrowers who get adjustable-rate mortgages should try to time their ARM’s initial rate period with their plans for the home. No one can be 100 percent certain about their future housing needs, so buyers may want to overestimate how long they’ll need a stable rate.

Think you’ll move in five years? Why not play it a little safer with a 7/1 ARM instead of a 5/1 ARM? That way you’ll have a little flexibility if your plans get delayed.

What happens when the ARM adjusts?

When it’s time for a 5/1 ARM to adjust, here’s what happens.

• Index syncing: The ARM syncs back up with the current index rate. If the index rate, usually the SOFR, was 3.5 percent when you opened the loan and it’s 4.5 percent now, the ARM will now match the new 4.5 percent index rate. Likewise, if the index rate has fallen, the ARM will take the lower rate.
• Margin add-on: The index changes, but the margin does not. If the ARM opened with a margin of 2.5 percent, the same 2.5 percent margin will be added to the new rate.
• Cap and floor check: Does the new rate fall within the limits set by the cap and the rate floor? If not, the rate will be contained to these limits. For instance, with a 2/1/5 cap, the loan’s first adjustment can’t exceed 2 percentage points, even if the index has increased by 2.5 or 3 percent. If the ARM’s floor is 2.5 percent, its rate won’t fall lower than that.

What does this mean in real life?

Let’s say you got a $300,000 loan using a 5/1 ARM and it’s now time for the loan to adjust. For the past five years you’ve had a rate of 5.5 percent and have been paying $2,050 a month, including property taxes and homeowners insurance.

All your regular mortgage payments, made over the first five years, have reduced your loan’s balance to $276,950. That new balance, not the original $300,000 loan size, will now be subject to the new interest rate.

So, what will happen to your monthly payment if you experienced:

• A marginal rate increase: Let’s say the economy has stayed about the same and now your rate is going up to 6 percent from its original 5.5 percent. The new monthly payment will go up by $80, to $2,130.
• A bigger rate increase: What if rates are a lot higher now, and yours goes up to 7 percent? That would require a payment increase of $253, to $2,303.
• The biggest rate increase: If the rate increased to the limit allowed by a standard 2 percent cap? That would mean paying 7.5 percent, adding $343, making the monthly payment $2,393.

Of course, rates could also go down. If the 5.5 percent rate became 4.75 percent, the payment would be $1,924, down $126 from the original $2,050.

All of these examples assume the property taxes and homeowners insurance premiums for this home stayed the same. In reality, these could change, causing changes to monthly payments.

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Common misconceptions about adjustable-rate mortgage loans

Like all financial tools, ARMs should be used for a specific purpose. For many borrowers this means having an exit plan in place before entering the loan.

Using ARMs without planning for their weaknesses as well as their strengths could cost borrowers more money than the loan saves, depending on how rates change in the future.

This potential for uncertainty has fueled some common misconceptions about ARMs:

Frequently Asked Questions about 5/1 ARMs

I'm planning to sell my house in about 6 years. Does a 5/1 ARM make sense for me?

Maybe, but a 7/1 ARM offers more predictability. With a 5/1 ARM you'd get five years at the lower fixed rate. Then you’d experience one rate adjustment before selling the home. Whether the rate increases or decreases will depend on market conditions at the time the rate adjusts. With a 7/1 ARM your interest rate will not increase if you sell the home in six years.

How much could my rate go up after the initial 5 years?

A 5/1 ARM’s interest rate could go up as high as the loan’s cap allows. With a standard 2/1/5 cap, the ARM’s rate could go up by 2 percentage points when it adjusts for the first time, which happens after the 5-year rate lock expires. Whether the loan’s rate reaches the cap, increases by a smaller amount, or decreases will depend on market conditions at the time of the adjustment.

What index is my 5/1 ARM tied to?

Most new ARMs are tied to SOFR, which is the Federal Reserve’s Standard Overnight Financing Rate. The Fed adjusts this rate every couple months with the goal of creating a stabler economy. During economic recessions, the Fed tends to lower its SOFR; in periods with high inflation, the Fed often raises the SOFR.

If rates drop after my ARM adjusts, does my payment go down?

Yes. An ARM’s adjustment can move in either direction, but the rate won’t fall lower than the ARM’s floor. The floor rate is set at the beginning of the loan’s term. For example, if your ARM’s floor is 2.5 percent, the rate will never fall below 2.5 percent.

Can I refinance out of a 5/1 ARM before it adjusts?

Yes, and this is what many ARM borrowers plan to do. ARMs can be a good fit for homebuyers who know they’ll be refinancing within a few years to take advantage of an improved credit score or higher monthly income.

Is a 5/1 ARM riskier than a 30-year fixed?

A 5/1 ARM brings more uncertainty than a 30-year fixed-rate loan. A 30-year fixed keeps its rate for all 30 years. A 5/1 ARM keeps its rate for only five years. Then its rate changes annually. The higher cost of a 30-year rate pays for more certainty.

What's the difference between a 5/1 ARM and a 7/1 ARM?

The fixed period for a 5/1 ARM lasts five years; a 7/1 fixed rate lasts seven years. Both loans adjust annually after their fixed periods expire. Typically, a 7/1 ARM has a slightly higher interest rate since the borrower gets two extra years of rate stability.

Conclusion

Some home buyers need only a few years of interest rate stability. A 5/1 ARM helps them pay for the stability they need instead of paying a higher rate that stays the same for 30 years.

Of course, any homeowner’s plans can change as time passes. If an ARM borrower needs to stay in the loan beyond its intro rate period, the ARM’s rate caps can help contain the uncertainty.

If your timeline lines up, the initial savings can be meaningful. If you're uncertain about your plans, a fixed rate may be worth the extra price for peace of mind.

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