The trade-off in one example
Borrow $400,000. At 5.75% for 15 years the payment is $3,321.64 and total interest is $197,895. At 6.5% for 30 years the payment is $2,528.27, $793.37 less each month, but total interest is $510,180: $312,285 more.
How big is the rate gap in practice? In Freddie Mac's weekly mortgage survey, the 15-year fixed rate averaged 0.68 percentage points below the 30-year over the year to September 17, 2026, when the two stood at 6.26% and 6.95%. Over that year the weekly gap ranged from 0.54 to 0.81 points. Lenders quote their own rates, so compare real Loan Estimates for both terms.
Calculated with the same engine as the calculator above. The rates are examples, not quotes.
The middle path: a 30-year paid like a 15-year
Taking the 30-year loan and voluntarily paying the 15-year amount gets you most of the savings while keeping a lower required payment as a safety net. It costs more than a true 15-year loan because the rate is higher, and it only works if you actually keep paying extra. The calculator's third row shows exactly what that flexibility costs.
Or take the 30-year and invest the difference
The other case for a 30-year loan is investing the monthly difference instead. That can come out ahead if your investments beat the 30-year rate after tax, but only if you actually invest the money every month, and returns aren't guaranteed. The pay extra vs invest calculator shows the return you'd need to beat, and the principal vs interest calculator shows when each loan's payments start going mostly to principal.
Questions to ask yourself
- Would the 15-year payment still be comfortable if your income dropped or a big bill arrived?
- Do you have an emergency fund and retirement savings on track at the higher payment?
- Would you really invest the difference if you took the 30-year? Compare in the pay extra vs invest calculator.
Questions people ask
Is a 15-year or 30-year mortgage better?
A 15-year loan usually has a lower rate and costs far less interest, but the payment is much higher. A 30-year loan has a lower required payment and more flexibility. The right choice depends on whether the higher payment fits comfortably alongside savings and emergencies.
Why are 15-year mortgage rates lower?
Lenders take less risk when they're repaid in half the time, so 15-year fixed rates are typically lower than 30-year rates. Check current quotes from lenders for the actual gap on your loan.
Can I get a 30-year loan and pay it like a 15-year?
Yes, if your loan has no prepayment penalty, which most don't. You'll pay the 30-year rate, so it costs more interest than a true 15-year loan, but you can drop back to the lower payment any time money is tight. The calculator shows the cost of that flexibility.
What about a 20-year mortgage?
A 20-year loan sits in between: a lower payment than 15 years and much less interest than 30. You can model it with the extra payment calculator by paying a 30-year loan faster.
For education and estimates only; not financial, tax or legal advice. Your lender's figures are final. See How we calculate.