An adjustable-rate mortgage (ARM) can make sense if you’re confident you’ll sell or refinance before the rate starts to change, and you could still afford the payment if that doesn’t happen. If either of those is uncertain, a fixed rate is usually the safer fit. The right choice depends on your plan, not on the lower number at the top of the page.
This guide compares a fixed vs adjustable-rate mortgage on five things: the starting payment, the rate caps, the lifetime cost, how long you’ll keep the loan, and the risk of counting on a future refinance.
What the Latest MBA Data Shows
Higher fixed rates are pushing some borrowers toward ARMs. In the Mortgage Bankers Association’s weekly survey for the week ending October 30, released on November 4, the average 5/1 ARM contract rate was 6.29%. The 30-year fixed conforming rate was 7.30%. ARMs made up 11.4% of applications, up from 11.3% the week before.
That’s a gap of about one percentage point. Freddie Mac’s separate survey put the 30-year fixed rate at 7.18% on November 5 . Rates move every week, so treat these figures as a snapshot. The comparison method below works at any rate level.
How Each Loan Works
A fixed-rate mortgage keeps the same interest rate and the same principal-and-interest payment for the whole term. You always know what you owe.
A common ARM starts with a fixed period, often 5, 7 or 10 years. After that, the rate adjusts on a schedule, usually once a year. A 5/6 ARM, for example, is fixed for five years and then adjusts every six months. Conventional ARMs are tied to an index called SOFR. Your new rate is the index plus a margin set in your loan documents.
Five Ways to Compare
1. The Initial Payment
An ARM’s lower starting rate means a lower payment at first. On a $400,000 loan, a 6.29% ARM costs about $2,473 a month in principal and interest. A 30-year fixed loan at 7.30% costs about $2,742. That’s roughly $269 less each month, or about $16,100 over five years.
2. The Adjustment Caps
Caps limit how far the rate can move. They typically come in three parts: how much it can change at the first adjustment, how much it can change at each later adjustment, and how high it can go over the life of the loan. Many standard conventional ARMs carry a 2% limit per adjustment and a 5% lifetime limit, though the first adjustment cap varies. Your Loan Estimate shows your exact caps.
Caps don’t remove risk. A 5% lifetime cap on a 6.29% start still allows an 11.29% rate.
3. The Lifetime Cost
The chart below uses an illustrative $400,000 loan. It assumes a 2% cap at the first adjustment, 2% at each later one and a 5% lifetime cap. It shows the interest you’d pay under different outcomes.
| Option | Payment, years 1 to 5 | Payment after the first reset | Interest paid after 7 years | Interest paid after 10 years |
|---|---|---|---|---|
| 30-year fixed at 7.30% | $2,742 | $2,742 | $196,610 | $274,707 |
| ARM, rate stays at 6.29% | $2,473 | $2,473 | $168,138 | $234,093 |
| ARM, rises 1 point to 7.29% | $2,473 | $2,710 | $175,612 | $252,732 |
| ARM, rises 2 points to 8.29% | $2,473 | $2,955 | $183,103 | $271,493 |
| ARM, climbs to the 11.29% cap by year 8 | $2,473 | $2,955, then about $3,716 | $190,497 | $312,316 |
Please note: Terms vary by lender. This is an illustration, not a quote. Payments exclude taxes, insurance and mortgage insurance.
The ARM costs less through year seven in every scenario. That changes by year ten. In the 2-point scenario, the ARM roughly ties the fixed loan. If rates climb to the cap, the ARM costs about $37,600 more.
4. How Long You’ll Keep the Loan
Holding period is the biggest factor. If you’re likely to sell or refinance within the fixed period, you collect the lower payments and never face the reset. If you might stay for a decade, you’re taking on the risk that the rate rises while you’re still in the loan.
5. The Risk of Depending on a Refinance
Many ARM borrowers plan to refinance before the rate adjusts. That’s a plan, not a guarantee. A refinance requires you to qualify again, and you’ll have closing costs. On the example above, refinancing at year five would cost roughly $9,300 if closing costs are 2.5% of the $373,500 balance. That would eat up more than half of the $16,100 you saved.
Your rate options, home value, credit and income at that time are unknown today. If any of them is worse, the refinance may be harder or more expensive. How to Refinance Your Mortgage in Texas explains how to evaluate a refinance when the time comes.
Qualifying for an ARM
The lower starting payment may not mean you can borrow more. Under Fannie Mae’s conventional rules, an ARM with an initial fixed period of five years or less is qualified at a rate above the starting rate. The qualifying rate is often the higher of the initial rate plus 2% or the fully indexed rate, per the Selling Guide’s ARM requirements . In the example, that’s closer to $3,016 a month.
Longer fixed periods, such as 7 or 10 years, can be treated differently. Ask your lender how your specific loan will be qualified.
When Each Option May Fit
An ARM may fit if:
– You expect to sell or move before the fixed period ends.
– You could comfortably afford the payment at the lifetime cap.
– You have reserves to absorb a higher payment.
– You understand the caps, the index and the margin.
A fixed rate may fit if:
– You plan to stay for many years.
– A stable payment matters to your budget.
– A payment increase would put you under real pressure.
– You’d rather not depend on a future refinance.
Some buyers also consider a fixed rate with a rate buydown instead. Permanent vs. Temporary Buydowns compares that route.
Questions to Ask Your Lender
– What is the initial fixed period, and how often does the rate adjust afterward?
>– When and what are the first-adjustment, periodic and lifetime caps?
>– What index and margin apply?
>– How would my payment change at each cap?
>– Is there a prepayment penalty, and can I convert to a fixed rate?
>– At what rate will you qualify me?
Mortgage Planner’s Perspective
The lowest starting rate is only one number. Planning compares the whole picture: the payment today, the worst-case payment later, the cost over the years you expect to hold the loan, and what happens if the plan changes. Why the Lowest Interest Rate Isn’t Always the Lowest Cost explains why rate alone can mislead.
An ARM can be a smart tool for the right borrower. The best way to know is to compare a fixed vs adjustable-rate mortgage side by side with your own numbers. Our mortgage calculators can help you start.
This article is general information. Rates, caps and program rules vary by lender and change over time, and the examples are illustrations, not offers. Talk with a licensed mortgage professional about your situation.
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RELATED ARTICLES
Why the Lowest Interest Rate Isn’t Always the Lowest Cost
How to Refinance Your Mortgage in Texas: A Step-by-Step Guide
Permanent vs. Temporary Buydowns
How Much House Can You Afford?
How Much Cash Reserves Do You Need for a Mortgage?
FREQUENTLY ASKED QUESTIONS
Choosing Between the Two
Q: Should I choose an adjustable-rate mortgage instead of a fixed-rate mortgage?
A: It can make sense if you expect to sell or refinance before the rate adjusts and could afford the payment if you don’t. If you plan to stay long term or need a predictable payment, a fixed rate is usually the safer fit.
Q: What is a 5/1 or 5/6 ARM?
A: It has a fixed rate for the first five years, then adjusts on a set schedule. A 5/1 adjusts once a year, and a 5/6 adjusts every six months.
Q: Is an ARM cheaper than a fixed-rate mortgage?
A: At first, usually yes. Over the full loan, it depends on how rates move and how long you keep the loan.
Caps and Risk
Q: What are ARM rate caps?
A: Caps limit how much the rate can rise at the first adjustment, at each later adjustment, and over the life of the loan. Check your Loan Estimate for yours.
Q: Can I refinance an ARM before it adjusts?
A: Often, but it’s not guaranteed. You’d need to qualify at that time and pay closing costs, so don’t treat it as a certainty.
Q: Will an ARM help me qualify for a bigger loan?
A: Not necessarily. For ARMs with shorter fixed periods, lenders may qualify you at a rate above the starting rate.
Texas Mortgage Plan – 50+ years of combined mortgage experience, serving homeowners and homebuyers across Flower Mound and the DFW Metroplex. Elizabeth Rose, NMLS 252686, CDLP® Certified Divorce Lending Professional | Shea Patton, Mortgage Advisor, NMLS #251397, Licensed Realtor. Texas Mortgage Plan is a d/b/a of Legacy Mortgage, NMLS #1759275 | Equal Housing Lender