15-Year vs 30-Year Mortgage: The Payment, the Interest and a Middle Way
On a $320,000 loan: the monthly cost of each, the interest saved, and how paying a 30-year loan like a 15-year one works.
By the MoneyBackKit team · Updated October 27, 2026 · 4 min read
A 15-year mortgage usually comes with a lower rate and saves a huge amount of interest. A 30-year mortgage has a much lower payment and more flexibility. The best choice is often a mix.
$320,000 loan (a $400,000 home with 20% down)
| 30 years at 6.5% | 15 years at 5.75% | |
|---|---|---|
| Monthly principal and interest | $2,022.62 | $2,657.31 |
| Total interest | $408,142 | $158,316 |
The 15-year loan costs $635 more a month but saves $249,826 of interest.
The middle way
Take the 30-year loan and pay the extra $635 a month anyway. At the 30-year rate it's paid off in about 16.3 years and saves $209,839 of interest. You pay a bit more than with a real 15-year loan, but if money gets tight you can drop back to the lower payment.
When the 30-year makes more sense
- You don't yet have 3–6 months of emergency savings.
- You aren't getting your full 401(k) match, or you carry credit card debt.
- Your income is irregular (commission, self-employed).