Adjustable-Rate Mortgages in San Antonio: The 6.69% vs. 7.40% Math

The rate gap, straight from the data

Freddie Mac's Primary Mortgage Market Survey held the 30-year fixed at 7.40% for the weeks of October 8 and October 15, 2026, after a jump from 7.28% in the first week of October. Adjustable products trade below that, and because Freddie Mac retired its old weekly 5/1 ARM series in late 2022, the honest reference is a compiled lender average: Fortune's survey of major lenders put the conforming 7/6 ARM at about 6.69% on October 20, and Experian's national average put the 5/1 ARM near 6.85% in October. No two quotes are identical, because loan size, points, and credit move every number, but the direction is consistent across the sources: ARMs are running half a point to three-quarters of a point below the fixed.

• Mortgage rates hit 7.28% in October: what San Antonio buyers should know
• Are mortgage points worth it at 7.40%? The break-even math

The payment math at $300,000

Run the same $300,000 loan at both rates and the numbers are concrete: at 7.40% the principal and interest payment is about $2,077 a month, and at 6.69% it is about $1,933, a difference of roughly $144 a month. Over the ARM's seven-year fixed period that is about $12,100 you keep versus taking the fixed rate, and the savings start in month one if the ARM quote comes with no points. If the adjustable quote does carry points, run the same break-even math you would for a fixed-rate buydown before you compare them. The whole question that remains is what happens in year eight, and that is answered by caps, the index, and the market, not by the rate sheet in front of you.

Who the ARM actually fits

Timeline first, rate second. If you expect to sell, relocate, or refinance within roughly seven years, the 7/6 ARM's fixed period covers most of your mortgage's active life and you collect the savings with almost no reset exposure. If you plan to hold the loan for 15 or 30 years, you are trading a guaranteed 7.40% for a rate that resets in year eight, and certainty is worth real money even when it is not the cheapest option in month one. Buyers who qualify at the edge of their budget should weigh the worst case before they sign: what the payment becomes at the maximum adjustment.

• Moving or selling within seven years, including a typical JBSA assignment cycle: the 7/6 ARM almost always wins on pure math, because the savings are locked in for the entire fixed period.
• Holding a mortgage for a decade or more with no refinance plan: the fixed rate wins, because the ARM's reset risk compounds the longer you hold it.
• A refinance plan as the escape hatch: if rates fall in years one through seven, you can refinance out of either loan, and the ARM gave you thousands in savings while you waited.
• Comfort with the worst case: know the caps (commonly up to 2 percentage points per adjustment and 5 to 6 over the life) and ask for a written payment illustration at the maximum first adjustment before you decide.

The fine print that decides it

• Rate caps. Most 7/6 ARMs cap each six-month adjustment at 2 percentage points and the total increase over the life of the loan at 5 to 6 points; the first adjustment is when the largest move can happen.
• Index and margin. The adjustable rate is typically the SOFR index plus a margin around 2 points; your lender should put both in writing on the loan estimate.
• Conversion option. Some lenders allow a 7/6 ARM to convert to a fixed-rate loan at the first adjustment, usually for a fee; ask whether yours does and what the fee runs.
• Points on the quote. If the 6.69% figure includes discount points, that changes the comparison entirely; run the break-even from the points article before treating the rates as equal.
• Prepayment. Confirm there is no prepayment penalty; most conforming ARMs today carry none, but it belongs on the written question list.

Questions to ask before you sign

Ask for both the fixed and the ARM quote with zero points on the same day, the exact caps and margin on the ARM, a written worst-case payment at the first adjustment, whether the loan can convert to fixed, and what rate in year eight would make the ARM the wrong call for your numbers. Write the answers down and run them against your own timeline. If the decision still feels close after the math, that is the signal to lean toward certainty: the fixed loan never surprises you at year eight.

Frequently asked questions