15-Year vs. 30-Year Mortgage in 2026: The Real 10-Year Numbers, Including What You'd Need to Earn Investing the Difference
Correction October 26, 2026: an earlier version attributed the 15-year loan’s faster principal paydown to its lower rate, and described the 2010-2021 gap between 30-year and 15-year rates as smaller than today’s. The paydown gap is almost entirely a function of the 15-year term, recomputed here on this article’s own $400,000 example, and the 30-year-minus-15-year spread has sat both above and below today’s 0.69 points within the past year. Source: Freddie Mac Primary Mortgage Market Survey. As of September 17, 2026, Freddie Mac's Primary Mortgage Market Survey puts the average 30-year fixed rate at 6.95% and the average 15-year fixed rate at 6.26%. The standard personal-finance advice for decades has been: take the 30-year loan for the lower payment, then invest the difference — you'll come out ahead because stocks have historically returned more than a mortgage costs. That advice is a real trade-off, not a rule, and at today's rate level the math is closer than...