Data Analysis

Redfin found that over the past half century, homebuyers would have saved money by choosing an adjustable-rate mortgage about 70% of the time, and that 71.6% of adjustable-rate borrowers got a chance to refinance into a fixed rate at least half a point lower within five years.

The analysis, published September 4, 2026, covers Freddie Mac survey data back to 1970. At the rates Redfin reported at the start of September, the gap between an adjustable and a fixed loan is worth about $92 a month on a loan the size of Florida's median single-family purchase.

Over the past half century, homebuyers would have saved money by choosing an adjustable-rate mortgage about 70% of the time, according to a Redfin analysis published September 4, 2026 by Dana Anderson and Yingqi Xu. The same analysis found that 71.6% of borrowers who take out an adjustable-rate mortgage get a chance to refinance into a 30-year fixed rate at least 0.5 percentage points lower, and that 52.8% get a chance to refinance a full percentage point lower. Redfin reported the average 30-year fixed rate at 6.88% at the start of September against an average adjustable rate of 6.47%.

That 41 basis point gap is the whole question for a Florida buyer this fall. Freddie Mac's Primary Mortgage Market Survey put the 30-year fixed at 6.71% for the week ending September 3, 2026, up from 6.66% the prior week and 6.50% a year earlier. Rates have been climbing slowly for a month. Buyers who have watched the fixed rate drift up all summer are the exact audience for a loan that starts lower.

What did Redfin actually measure?

Redfin analyzed Freddie Mac's Primary Mortgage Market Survey data going back through 1970. The firm counted a borrower as having an opportunity to refinance when the prevailing 30-year fixed rate fell at least 50 basis points below the rate that borrower was carrying, and it required that opportunity to last at least one full quarter. A second, narrower test used a 100 basis point gap. For each origination quarter, Redfin looked at rates nine months to five years later, skipping the first nine months because lenders typically do not allow a refinance until at least six months after origination, and stopping at five years because that is the fixed period on a 5/1 adjustable loan.

Two figures in the report are close together and measure different things. The 70% figure is how often a buyer would have come out ahead by taking the adjustable loan. The 71.6% figure is how often an adjustable borrower later got a window to refinance into a cheaper fixed rate. A buyer can have the second without the first, and the report treats them separately.

Redfin's illustration uses a hypothetical borrower rather than a market average. In it, a buyer who takes a 30-year fixed mortgage at 6.5% pays about $3,160 a month, while the same buyer taking a 5/1 adjustable loan with an introductory rate of 5.75% saves about $14,500 over five years. If that borrower refinances at the end of the introductory period, Redfin puts the further saving at about $9,000, for roughly $23,000 less in total mortgage payments.

How much would an adjustable loan save a Florida buyer right now?

Florida Realtors reported a statewide median single-family sale price of $425,000 for July 2026, up 3.7% from a year earlier, in its August 17 release. Closed sales came to 23,870, up 5.1%, with 4.5 months of supply. A buyer paying that median price with 20% down finances $340,000.

At the rates Redfin reported at the start of September, that loan costs about $2,235 a month in principal and interest at the 6.88% fixed rate and about $2,142 at the 6.47% adjustable rate. The difference is roughly $92 a month, or about $5,540 over the five-year introductory period. The adjustable borrower also pays the balance down slightly faster, owing about $1,470 less after 60 payments. These are Momentum Research calculations on a 30-year amortization, principal and interest only. They exclude property taxes, homeowners insurance and any mortgage insurance, which matter more in Florida than in most states.

For scale, the same $340,000 loan at Freddie Mac's 6.71% weekly average costs about $2,196 a month. Freddie Mac's weekly survey and Redfin's rate series are different measurements taken on different days, and the two should not be read as one series.

What are the risks of an adjustable-rate mortgage?

The rate resets. A 5/1 loan carries its introductory rate for five years, after which it adjusts on a schedule tied to an index. Redfin's own framing is that "ARMs aren't nearly as risky as they once were; new rules went into effect after the financial crisis to protect borrowers," and that these loans "come with interest-rate caps, which limit how much the rate is allowed to increase each term and over the life of the loan."

Caps limit the damage without removing it. The historical case for the adjustable loan rests on refinancing windows appearing, and 28.4% of the borrowers in Redfin's analysis never got even the half-point window inside five years. A buyer who plans to stay in the home well past the introductory period, and who would struggle with a higher payment if no refinance window opened, is carrying a risk the averages do not describe.

Florida adds its own variable. Insurance and association dues have moved enough in recent years that the monthly cost of owning a home here can change substantially while the mortgage rate sits still. A $92 monthly saving on the loan can be erased by a single insurance renewal.

What does this mean for Florida buyers this fall?

Statewide inventory sat at 4.5 months in July, which is a market with room to negotiate rather than one moving quickly. Buyers in that position have time to price both loan types with a lender and to ask what the adjustable loan's caps and index actually are. The Redfin analysis is a statement about the past 50 years of rate history, and it is a reasonable input. It is not a forecast, and Redfin does not present it as one.

The desk tracks the statewide picture on the Florida housing tracker, with metro detail for Miami and Tampa.

Limitations

Redfin does not have adjustable-rate data back to 1970. Freddie Mac's 5/1 adjustable series begins in 2005. Redfin observed that the adjustable rate was consistently below the 30-year fixed rate over the 2005 to 2022 period and extended that assumption across the full historical window, so the pre-2005 portion of the 70% finding rests on an assumption rather than on observed adjustable rates.

The report's refinance test counts an opportunity when a window opens and lasts a quarter. It does not model closing costs, credit qualification at the time of the refinance, or whether the borrower acts. Real refinancing is more expensive and less certain than the test allows.

The $14,500, $9,000 and $23,000 figures come from Redfin's hypothetical borrower at a 6.5% fixed rate and a 5.75% introductory rate. Those are not September 2026 market rates and should not be read as what a buyer would save today. The Florida payment figures in this article are the desk's own arithmetic on the rates Redfin reported, not Redfin's calculations.

The report is national. It contains no Florida or Florida metro figures, and nothing in it describes conditions in any Florida market.

Sources

Redfin, "History Shows That Adjustable-Rate Mortgages Pay Off For Homebuyers Most of the Time," Dana Anderson and Yingqi Xu, September 4, 2026: https://www.redfin.com/news/arm-versus-fixed-rate-mortgage/

Freddie Mac Primary Mortgage Market Survey, week ending September 3, 2026: https://www.freddiemac.com/pmms

Florida Realtors, "Fla.'s Housing Market: Closed Sales and New Pending Sales Rise in July," released August 17, 2026: https://www.floridarealtors.org/newsroom/flas-housing-market-closed-sales-and-new-pending-sales-rise-july

Payment calculations by Momentum Research on a $340,000 30-year loan, principal and interest only.

Disclosure: Jon Brooks is a co-founder of Momentum Realty, a Florida real estate brokerage that owns and funds Florida Housing Intelligence. Momentum has a financial interest in Florida real estate transactions, including in markets named here. See our editorial standards.